Imaging element, stacked imaging element and solid-state imaging device, and method of manufacturing imaging element

ABSTRACT

An imaging element of the present disclosure includes a photoelectric conversion section including a first electrode 21, a photoelectric conversion layer 23A including an organic material, and a second electrode 22 that are stacked; an inorganic semiconductor material layer 23B is formed between the first electrode 21 and the photoelectric conversion layer 23A; and a value ΔEN (=ENanion−ENcation) is less than 1.695, and preferably 1.624 or less, which results from subtracting an average value ENcation of electronegativities of cationic species included in the inorganic semiconductor material layer from an average value ENanion of electronegativities of anionic species included in the inorganic semiconductor material layer 23B.

TECHNICAL FIELD

The present disclosure relates to an imaging element, a stacked imagingelement and a solid-state imaging device, and to a method ofmanufacturing the imaging element.

BACKGROUND ART

In recent years, a stacked imaging element is drawing attention as animaging element configuring an image sensor or the like. The stackedimaging element has a structure in which a photoelectric conversionlayer (light receiving layer) is sandwiched between two electrodes. Inaddition, it is necessary that the stacked imaging element have astructure for accumulating and transferring signal charge generated inthe photoelectric conversion layer on the basis of photoelectricconversion. In a currently available structure, it is necessary toprovide a structure in which the signal charge is accumulated in andtransferred to a FD (Floating Drain) electrode, and it is necessary toachieve such fast transfer as to avoid delay of the signal charge.

An imaging element (photoelectric conversion element) for solving suchan issue is disclosed in, for example, Japanese Unexamined PatentApplication Publication No. 2016-063165.

The imaging element in which an organic semiconductor material is usedfor a photoelectric conversion layer is able to perform photoelectricconversion of a specific color (wavelength band). Having such acharacteristic, in the case where the imaging element is used as animaging element in a solid-state imaging device, it is possible toobtain a structure including stacked subpixels (stacked imaging element)that is difficult to obtain with an existing solid-state imaging device.In the structure, a combination of an on-chip color filter layer (OCCF)and an imaging element constitutes a subpixel, and the subpixels arearranged in a two-dimensional pattern (see, for example, JapaneseUnexamined Patent Application Publication No. 2011-138927). Furthermore,because a demosaic treatment is unnecessary, the imaging element has anadvantage of not generating false colors. In the following description,in some cases, an imaging element including a photoelectric conversionsection provided on or above a semiconductor substrate is referred to asan “imaging element of a first type” for the sake of convenience; thephotoelectric conversion section included in the imaging element of thefirst type is referred to as a “photoelectric conversion section of thefirst type” for the sake of convenience; an imaging element provided inthe semiconductor substrate is referred to as an “imaging element of asecond type” for the sake of convenience; and a photoelectric conversionsection included in the imaging element of the second type is referredto as a “photoelectric conversion section of the second type” for thesake of convenience.

Meanwhile, Japanese Unexamined Patent Application Publication No.2006-165527 discloses an invention of a field-effect transistor, inwhich an amorphous oxide applicable to an active layer of thefield-effect transistor is described. In addition, in paragraph number[0146] of this patent publication, there is a description “It ispossible to add an element constituting at least one complex oxide, fromamong a Group 2 element M2 (M2 denotes Mg or Ca) having a smaller atomicnumber than that of Zn, a Group 3 element M3 (M3 denotes B, Al, Ga, orY) having a smaller atomic number than that of In, a Group 4 element M4(M4 denotes Si, Ge, or Zr) having a smaller atomic number than that ofSn, a Group 5 element M5 (M5 denotes V, Nb, or Ta), Lu, and W.” Inparagraph numbers [0147] and [0148], there is a description “This makesit possible to further stabilize the amorphous film at room temperature.In addition, it is possible to expand a composition range in which theamorphous film is obtained. In particular, the addition of B, Si, or Gehaving a strong covalent bonding property is effective for stabilizationof the amorphous phase, and a complex oxide containing ions having alarge difference in ionic radii has stabilized amorphous phase.”

CITATION LIST Patent Literature

PTL 1: Japanese Unexamined Patent Application Publication No.2016-063165

PTL 2: Japanese Unexamined Patent Application Publication No.2011-138927

PTL 3: Japanese Unexamined Patent Application Publication No.2006-165527

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

The technique disclosed in Japanese Unexamined Patent ApplicationPublication No. 2006-165527 is a technique for further stabilizing theamorphous film at room temperature, and is a technique for expanding thecomposition range in which the amorphous film is obtained; no referenceis made to the above-mentioned parameters related to improved transferor the like of electric charge in a stacked structure of a photoelectricconversion layer including an organic material and an inorganicsemiconductor material layer. In addition, Japanese Unexamined PatentApplication Publication No. 2006-165527 describes an empirical rule inwhich addition of dopants B, Si, or Ge having a strong covalent bondingproperty allows an amorphous phase to appear more easily than acrystalline phase, but does not make any reference to an index ΔEN inwhich a covalent bonding property of the entire material is quantifiedor to a criterion for selecting a dopant.

Therefore, a first object of the present disclosure is to provide animaging element, a stacked imaging element and a solid-state imagingdevice which have superior characteristics of transferring electriccharge accumulated in a photoelectric conversion layer despite simpleconfiguration and structure. Further, in addition to the first object ofthe present disclosure, a second object of the present disclosure is toprovide a method of manufacturing an imaging element exhibiting superiorcharacteristics even by annealing process at a low temperature.

Means for Solving the Problem

An imaging element of the present disclosure to achieve theabove-described first object includes a photoelectric conversion sectionincluding a first electrode, a photoelectric conversion layer includingan organic material, and a second electrode that are stacked, aninorganic semiconductor material layer is formed between the firstelectrode and the photoelectric conversion layer, and

a value ΔEN(=EN_(anion)−EN_(cation)) is less than 1.695, and preferably1.624 or less, which results from subtracting an average valueEN_(cation) of electronegativities of cationic species included in theinorganic semiconductor material layer from an average value EN_(anion)of electronegativities of anionic species included in the inorganicsemiconductor material layer.

A stacked imaging element of the present disclosure to achieve theabove-described first object includes at least one of theabove-described imaging elements of the present disclosure.

A solid-state imaging device according to the first aspect of thepresent disclosure to achieve the above-described first object includesa plurality of the above-described imaging elements of the presentdisclosure. In addition, a solid-state imaging device according to asecond aspect of the present disclosure to achieve the above-describedfirst object includes a plurality of the above-described stacked imagingelements of the present disclosure.

A method of manufacturing an imaging element of the present disclosureto achieve the above-described second object includes:

sequentially forming, on an underlayer in which a first electrode isformed, an inorganic semiconductor material layer, a photoelectricconversion layer including an organic material, and a second electrode;and

applying an annealing process at 250° C. or less in an atmospherecontaining water vapor after the formation of the inorganicsemiconductor material layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic partial cross-sectional view of an imaging elementof Example 1.

FIG. 2 is an equivalent circuit diagram of the imaging element ofExample 1.

FIG. 3 is an equivalent circuit diagram of the imaging element ofExample 1.

FIG. 4 is a schematic layout diagram of a first electrode and a chargeaccumulation electrode, and transistors included in a control sectionthat are included in the imaging element of Example 1.

FIG. 5 schematically illustrates a state of potential at each partduring operation of the imaging element of Example 1.

FIGS. 6A, 6B, and 6C are equivalent circuit diagrams of imaging elementsof Example 1, Example 4, and Example 6 for describing respective partsof FIG. 5 (Example 1), FIGS. 20 and 21 (Example 4), and FIGS. 32 and 33(Example 6).

FIG. 7 is a schematic layout diagram of the first electrode and thecharge accumulation electrode included in the imaging element of Example1.

FIG. 8 is a schematic transparent perspective view of the firstelectrode, the charge accumulation electrode, a second electrode, and acontact hole section included in the imaging element of Example 1.

FIG. 9 is an equivalent circuit diagram of a modification example of theimaging element of Example 1.

FIG. 10 is a schematic layout diagram of the first electrode and thecharge accumulation electrode, and the transistors included in thecontrol section that are included in the modification example of theimaging element of Example 1 illustrated in FIG. 9.

FIG. 11 is a schematic partial cross-sectional view of an imagingelement of Example 2.

FIG. 12 is a schematic partial cross-sectional view of an imagingelement of Example 3.

FIG. 13 is a schematic partial cross-sectional view of a modificationexample of the imaging element of Example 3.

FIG. 14 is a schematic partial cross-sectional view of anothermodification example of the imaging element of Example 3.

FIG. 15 is a schematic partial cross-sectional view of still anothermodification example of the imaging element of Example 3.

FIG. 16 is a schematic partial cross-sectional view of a portion of theimaging element of Example 4.

FIG. 17 is an equivalent circuit diagram of the imaging element ofExample 4.

FIG. 18 is an equivalent circuit diagram of the imaging element ofExample 4.

FIG. 19 is a schematic layout diagram of the first electrode, a transfercontrol electrode, and the charge accumulation electrode, and thetransistors included in the control section that are included in theimaging element of Example 4.

FIG. 20 schematically illustrates a state of potential at each partduring operation of the imaging element of Example 4.

FIG. 21 schematically illustrates a state of potential at each partduring another operation of the imaging element of Example 4.

FIG. 22 is a schematic layout diagram of the first electrode, thetransfer control electrode, and the charge accumulation electrodeincluded in the imaging element of Example 4.

FIG. 23 is a schematic transparent perspective view of the firstelectrode, the transfer control electrode, the charge accumulationelectrode, the second electrode, and the contact hole section includedin the imaging element of Example 4.

FIG. 24 is a schematic layout diagram of the first electrode, thetransfer control electrode and the charge accumulation electrode, andthe transistors included in the control section that are included in amodification example of the imaging element of Example 4.

FIG. 25 is a schematic partial cross-sectional view of a portion of animaging element of Example 5.

FIG. 26 is a schematic layout diagram of the first electrode, the chargeaccumulation electrode, and a charge drain electrode included in theimaging element of Example 5.

FIG. 27 is a schematic transparent perspective view of the firstelectrode, the charge accumulation electrode, the charge drainelectrode, the second electrode, and the contact hole section includedin the imaging element of Example 5.

FIG. 28 is a schematic partial cross-sectional view of an imagingelement of Example 6.

FIG. 29 is an equivalent circuit diagram of the imaging element ofExample 6.

FIG. 30 is an equivalent circuit diagram of the imaging element ofExample 6.

FIG. 31 is a schematic layout diagram of the first electrode and thecharge accumulation electrode, and the transistors included in thecontrol section that are included in the imaging element of Example 6.

FIG. 32 schematically illustrates a state of potential at each partduring operation of the imaging element of Example 6.

FIG. 33 schematically illustrates a state of potential at each partduring another operation (during transfer) of the imaging element ofExample 6.

FIG. 34 is a schematic layout diagram of the first electrode and thecharge accumulation electrode included in the imaging element of Example6.

FIG. 35 is a schematic transparent perspective view of the firstelectrode, the charge accumulation electrode, the second electrode, andthe contact hole section included in the imaging element of Example 6.

FIG. 36 is a schematic layout diagram of the first electrode and thecharge accumulation electrode included in a modification example of theimaging element of Example 6.

FIG. 37 is a schematic cross-sectional view of a portion of an imagingelement of Example 7 (two imaging elements arranged side by side).

FIG. 38 is a schematic layout diagram of the first electrode and thecharge accumulation electrode or the like, and the transistors includedin the control section that are included in the imaging element ofExample 7.

FIG. 39 is a schematic layout diagram of the first electrode and thecharge accumulation electrode or the like included in the imagingelement of Example 7.

FIG. 40 is a schematic layout diagram of a modification example of thefirst electrode and the charge accumulation electrode or the likeincluded in the imaging element of Example 7.

FIG. 41 is a schematic layout diagram of a modification example of thefirst electrode and the charge accumulation electrode or the likeincluded in the imaging element of Example 7.

FIGS. 42A and 42B are schematic layout diagrams of modification examplesof the first electrode and the charge accumulation electrode or the likeincluded in the imaging element of Example 7.

FIG. 43 is a schematic cross-sectional view of a portion of an imagingelement of Example 8 (two imaging elements arranged side by side).

FIG. 44 is a schematic plan view of a portion of the imaging element ofExample 8 (2×2 imaging elements arranged side by side).

FIG. 45 is a schematic plan view of a portion of a modification exampleof the imaging element of Example 8 (2×2 imaging elements arranged sideby side).

FIGS. 46A and 46B are schematic cross-sectional views of portions ofmodification examples of the imaging element of Example 8 (two imagingelements arranged side by side).

FIGS. 47A and 47B are schematic cross-sectional views of portions ofmodification examples of the imaging element of Example 8 (two imagingelements arranged side by side).

FIGS. 48A and 48B are schematic plan views of portions of themodification examples of the imaging element of Example 8.

FIGS. 49A and 49B are schematic plan views of portions of themodification examples of the imaging element of Example 8.

FIG. 50 is a schematic plan view of the first electrodes and chargeaccumulation electrode segments in a solid-state imaging device ofExample 9.

FIG. 51 is a schematic plan view of the first electrodes and the chargeaccumulation electrode segments in a first modification example of thesolid-state imaging device of Example 9.

FIG. 52 is a schematic plan view of the first electrodes and the chargeaccumulation electrode segments in a second modification example of thesolid-state imaging device of Example 9.

FIG. 53 is a schematic plan view of the first electrodes and the chargeaccumulation electrode segments in a third modification example of thesolid-state imaging device of Example 9.

FIG. 54 is a schematic plan view of the first electrodes and the chargeaccumulation electrode segments in a fourth modification example of thesolid-state imaging device of Example 9.

FIG. 55 is a schematic plan view of the first electrodes and the chargeaccumulation electrode segments in a fifth modification example of thesolid-state imaging device of Example 9.

FIG. 56 is a schematic plan view of the first electrodes and the chargeaccumulation electrode segments in a sixth modification example of thesolid-state imaging device of Example 9.

FIG. 57 is a schematic plan view of the first electrodes and the chargeaccumulation electrode segments in a seventh modification example of thesolid-state imaging device of Example 9.

FIGS. 58A, 58B, and 58C are charts illustrating examples of reading anddriving in an imaging element block of Example 9.

FIG. 59 is a schematic plan view of the first electrodes and the chargeaccumulation electrode segments in a solid-state imaging device ofExample 10.

FIG. 60 is a schematic plan view of the first electrodes and the chargeaccumulation electrode segments in a modification example of thesolid-state imaging device of Example 10.

FIG. 61 is a schematic plan view of the first electrodes and the chargeaccumulation electrode segments in a modification example of thesolid-state imaging device of Example 10.

FIG. 62 is a schematic plan view of the first electrodes and the chargeaccumulation electrode segments in a modification example of thesolid-state imaging device of Example 10.

FIG. 63 is a schematic partial cross-sectional view of still anothermodification example of the imaging element and a stacked imagingelement of Example 1.

FIG. 64 is a schematic partial cross-sectional view of still anothermodification example of the imaging element and the stacked imagingelement of Example 1.

FIG. 65 is a schematic partial cross-sectional view of still anothermodification example of the imaging element and the stacked imagingelement of Example 1.

FIG. 66 is a schematic partial cross-sectional view of anothermodification example of the imaging element and the stacked imagingelement of Example 1.

FIG. 67 is a schematic partial cross-sectional view of still anothermodification example of the imaging element of Example 4.

FIG. 68 is a conceptual diagram of a solid-state imaging device ofExample 1.

FIG. 69 is a conceptual diagram of an example in which a solid-stateimaging device including the imaging element and the stacked imagingelement according to any of first and second aspects of the presentdisclosure is used in an electronic apparatus (camera).

FIG. 70 is a conceptual diagram of a stacked imaging element (stackedsolid-state imaging device) of a comparative example.

(A), (B), (C) and (D) of FIG. 71 schematically illustrate a stateimmediately after film formation of an inorganic semiconductor materiallayer and a state where dangling bonds disappear by applying anannealing process to the inorganic semiconductor material layer in anatmosphere containing water vapor, and (E), (F), (G) and (H) of FIG. 71schematically illustrate a state immediately after film formation of aninorganic semiconductor material layer and a state where hydrogen isdiffused and infiltrated to the inorganic semiconductor material layerin an atmosphere containing water vapor, thus accelerating formation ofmetal-hydrogen bonds.

FIG. 72 schematically illustrates electric distributions (electrostaticpotentials) of a material having a high covalent bonding property and amaterial having a high ionic bonding property.

FIG. 73 is a diagram for describing the reason why an element havingrelatively high electronegativity among metal elements is more likely togenerate a hydride ion.

(A), (B) and (C) of FIG. 74 are graphs illustrating results ofevaluation of TFT characteristics by forming a channel formation regionof a TFT from an inorganic semiconductor material layer, in Example 1A,Example 1B, and Comparative Example 1.

FIG. 75A and FIG. 75B are graphs illustrating results of evaluation of arelationship between VGS and ID in the TFT, as TFT characteristics, whensetting an annealing temperature from 250° C. through 280° C. to 350°C., and results of determination of aryl temperature and hydrogenconcentration, in Comparative Example 1 usingIn_(a1)Ga_(a2)Zn_(a3)O_(b1).

FIGS. 76A and 76B are, respectively, a graph plotting a relationshipbetween values of (a1, a2, and a3) and a definition of ΔEN being lessthan 1.695 in a case where an inorganic semiconductor material layercontains Al_(a1)Zn_(a2)Sn_(a3)O_(b1), and a graph indicating a regionsatisfying expressions (1), (2-1), (2-2), (3), and (4) of the values of(a1, a2, and a3).

FIG. 77 is a block diagram depicting an example of schematicconfiguration of a vehicle control system.

FIG. 78 is a diagram of assistance in explaining an example ofinstallation positions of an outside-vehicle information detectingsection and an imaging section.

FIG. 79 is a view depicting an example of a schematic configuration ofan endoscopic surgery system.

FIG. 80 is a block diagram depicting an example of a functionalconfiguration of a camera head and a camera control unit (CCU).

MODES FOR CARRYING OUT THE INVENTION

In the following, description is given of the present disclosure on thebasis of Examples with reference to the drawings. However, the presentdisclosure is not limited to Examples, and various numerical values andmaterials in Examples are illustrative. It is to be noted that thedescription is given in the following order.

1. General Description of Imaging Element of Present Disclosure, StackedImaging Element of Present Disclosure, Solid-State Imaging DevicesAccording to First and Second Aspects of Present Disclosure, and Methodof Manufacturing Imaging Element of Present Disclosure

2. Example 1 (Imaging Element of Present Disclosure, Stacked ImagingElement of Present Disclosure, Solid-State Imaging Device According toSecond Aspect of Present Disclosure, and Method of Manufacturing ImagingElement of Present Disclosure) 3. Example 2 (Modification of Example 1)4. Example 3 (Modification of Examples 1 and 2, Solid-State ImagingDevice According to First Aspect of Present Disclosure) 5. Example 4(Modification of Examples 1 to 3, Imaging Element Including TransferControl Electrode) 6. Example 5 (Modification of Examples 1 to 4,Imaging Element Including Charge Drain Electrode) 7. Example 6(Modification of Examples 1 to 5, Imaging Element Including a Pluralityof Charge Accumulation Electrode Segments) 8. Example 7 (Modification ofExamples 1 to 6, Imaging Element Including Charge Movement ControlElectrode) 9. Example 8 (Modification of Example 7) 10. Example 9(Solid-State Imaging Devices of First and Second Configurations) 11.Example 10 (Modification of Example 9) 12. Others

<General Description of Imaging Element of Present Disclosure, StackedImaging Element of Present Disclosure, Solid-State Imaging DevicesAccording to First and Second Aspects of Present Disclosure, and Methodof Manufacturing Imaging Element of Present Disclosure>

In the following, a term “an imaging element or the like of the presentdisclosure” is used in some cases to collectively refer to an imagingelement of the present disclosure, the imaging element of the presentdisclosure included in a stacked imaging element of the presentdisclosure, and the imaging element of the present disclosure includedin a solid-state imaging device according to the first aspect or asecond aspect of the present disclosure.

In a method of manufacturing the imaging element of the presentdisclosure, an annealing process may be at any stage of manufacturingprocesses after formation of an inorganic semiconductor material layer;the annealing process may be either after the formation of an inorganicsemiconductor material layer, after formation of a photoelectricconversion layer, after formation of a second electrode, or after elapseof various manufacturing steps after the formation of the secondelectrode. Specific examples of an atmosphere containing water vaporinclude an atmospheric atmosphere containing water vapor.

In the imaging element or the like of the present disclosure, a mode maybe adopted in which, when the inorganic semiconductor material layer isrepresented by (A¹ _(a1)A² _(a2)A³ _(a3) . . . A^(M) _(aM))(B¹ _(b1)B²_(b2)B³ _(b3) . . . B^(N) _(bN)) [where A¹, A², A³, . . . , and A^(M)are cationic species, B¹, B², B³, . . . , and B^(N) are anionic species,and a1, a2, a3, . . . , and aM, and b1, b2, b3, . . . , and bN arevalues corresponding to atomic percentages, with the total thereof being1.00],

${EN_{anion}} = \frac{\left( {{B\; 1 \times b\; 1} + {B\; 2 \times b\; 2} + {B\; 3 \times b\; 3\mspace{14mu}\ldots} + {B\; N \times b\; N}} \right)}{\left( {{b\; 1} + {b\; 2} + {b\; 3\mspace{14mu}\ldots} + {b\; N}} \right)}$${EN_{cation}} = \frac{\left( {{A\; 1 \times a\; 1} + {A\; 2 \times a\; 2} + {A\; 3 \times a\; 3\mspace{14mu}\ldots} + {A\; M \times a\; M}} \right)}{\left( {{a\; 1} + {a\; 2} + {a\; 3\mspace{14mu}\ldots} + {a\; M}} \right)}$

hold true, where B1, B2, B3, . . . , and BN are electronegativities ofthe anionic species B¹, B², B³ . . . , and B^(N), and A1, A2, A3, . . ., and A^(M) are electronegativities of cationic species A¹, A², A³ . . ., and A^(M).

In the imaging element or the like of the present disclosure includingthe preferred modes described above, a configuration may be adopted inwhich the cationic species include at least one type of cationic speciesselected from the group consisting of Zn, Ga, Ge, Cd, In, Al, Ti, B, Si,Sn, Hg, Tl, and Pb. In addition, a configuration may be adopted in whichthe anionic species include at least one type of anionic speciesselected from the group consisting of O, N, S, and F

Alternatively, in the imaging element or the like of the presentdisclosure including the preferred modes described above, aconfiguration may be adopted in which the cationic species include Ga,In, and Sn, and the anionic species include O. Alternatively, aconfiguration may be adopted in which the cationic species include Zn,Al, and Sn, and the anionic species include O.

In the imaging element or the like of the present disclosure includingvarious preferred modes and configurations described above, a mode maybe adopted in which a photoelectric conversion section further includesan insulating layer, and a charge accumulation electrode disposed at adistance from a first electrode and disposed to be opposed to theinorganic semiconductor material layer with the insulating layerinterposed therebetween.

Description is given later in detail of the first electrode, the secondelectrode, the charge accumulation electrode, and the photoelectricconversion layer.

Further, in the imaging element or the like of the present disclosureincluding the preferred modes and configurations described above, a modemay be adopted in which electric charge generated in the photoelectricconversion layer moves to the first electrode via the inorganicsemiconductor material layer. In this case, a mode may be adopted inwhich the electric charge is an electron.

Further, when it is defined that, with a vacuum level as a zeroreference, energy becomes higher as being away from the vacuum level, amode may be adopted in which a LUMO value E₀ of a material included inthe photoelectric conversion layer and a minimum energy value E₁ of aconduction band of an inorganic semiconductor material included in theinorganic semiconductor material layer (hereinafter, simply referred toas “inorganic semiconductor material” in some cases) satisfy thefollowing expressions:

E₁ ≥ E₀

desirably,

E₁ − E₀ ≥ 0.1  (eV)

and more desirably,

E₁ − E₀ > 0.1  (eV).

The minimum energy value E₁ of the conduction band of the inorganicsemiconductor material is an average value in the inorganicsemiconductor material layer. In addition, the LUMO value E₀ of thematerial included in the photoelectric conversion layer is an averagevalue in a portion of the photoelectric conversion layer positioned inthe vicinity of the inorganic semiconductor material layer. Here, the“portion of the photoelectric conversion layer positioned in thevicinity of the inorganic semiconductor material layer” refers to aportion of the photoelectric conversion layer positioned in a regioncorresponding to 10% or less of the thickness of the photoelectricconversion layer (i.e., a region extending from 0% to 10% of thethickness of the photoelectric conversion layer) with an interfacebetween the inorganic semiconductor material layer and the photoelectricconversion layer as a reference.

A valence band energy and a HOMO value are determinable on the basis of,for example, ultraviolet photoelectron spectroscopy (UPS method). Inaddition, a conduction band energy and a LUMO value are determinablefrom {(valence band energy, HOMO value)+E_(b)}. Further, the bandgapenergy E_(b) is determinable, from an optically absorbing wavelength λ(an optical absorption edge wavelength in nm), on the basis of thefollowing expression:

E_(b) = hv = h(c/λ) = 1239.8/λ  [eV].

The inorganic semiconductor material layer is provided to transferelectric charge generated in the photoelectric conversion layer to thefirst electrode; therefore, when a transfer rate is slow, it takes timeto read out a signal from the imaging element, thus making it hardlypossible to obtain an appropriate frame rate required by the solid-stateimaging device. In order to increase the transfer rate, carrier mobilityof the inorganic semiconductor material layer, i.e., field mobilityneeds to be increased. Therefore, in the imaging element or the like ofthe present disclosure including the various preferred modes andconfigurations described above, it is preferred that the inorganicsemiconductor material layer have a carrier mobility of 10 cm²/V·s ormore, which enables electric charge accumulated in the inorganicsemiconductor material layer to be quickly moved to the first electrode.

In the imaging element or the like of the present disclosure includingthe various preferred modes and configurations described above, theinorganic semiconductor material layer preferably has a carrier density(carrier concentration) of 1×10¹⁶/cm³ or less, which enables an increasein the amount of electric charge accumulated in the inorganicsemiconductor material layer.

In the imaging element or the like of the present disclosure includingthe various preferred modes and configurations described above, it isdesirable that the inorganic semiconductor material layer have athickness of 1×10⁻⁸ m to 1.5×10⁻⁷ m, preferably 2×10⁻⁸ m to 1.0×10⁻⁷ m,and more preferably, 3×10⁻⁸ m to 1.0×10⁻⁷ m.

In the imaging element or the like of the present disclosure includingthe various preferred modes and configurations described above, it ispreferred that:

light be incident from a second electrode; and

a surface roughness Ra of a surface of the inorganic semiconductormaterial layer at the interface between the photoelectric conversionlayer and the inorganic semiconductor material layer be 1.5 nm or less,and a root mean square roughness Rq of the surface of the inorganicsemiconductor material layer be 2.5 nm or less. The surface roughnessesRa and Rq are based on the provisions of JIS B0601:2013. Such smoothnessof the surface of the inorganic semiconductor material layer at theinterface between the photoelectric conversion layer and the inorganicsemiconductor material layer makes it possible to suppress scatteringreflection at the surface of the inorganic semiconductor material layer,and to enhance light current characteristic in photoelectric conversion.It is preferred that a surface roughness Ra of a surface of the chargeaccumulation electrode be 1.5 nm or less, and the root mean squareroughness Rq of the surface of the charge accumulation electrode be 2.5nm or less.

In the imaging element or the like of the present disclosure, theinorganic semiconductor material preferably has an optical gap of 2.8 eVor more and 3.2 eV or less, which enables the inorganic semiconductormaterial layer to be a transparent layer with respect to incident light,and eliminates the possibility of causing a barrier to movement ofelectric charge from the photoelectric conversion layer to the inorganicsemiconductor material layer. Alternatively, it is preferred that theinorganic semiconductor material have an optical gap of 3.0 eV or moreand 3.2 eV or less to allow the inorganic semiconductor material layerto be a layer transparent to incident light in a still wider wavelengthrange. That is, in order for the inorganic semiconductor material layerto reliably receive electric charge generated in the photoelectricconversion layer, the level of a conduction band of the inorganicsemiconductor material is required to be deeper than the level of aconduction band of a material included in the photoelectric conversionlayer; for that purpose, the inorganic semiconductor material preferablyhas an optical gap of 3.2 eV or less, for example.

In addition, in the imaging element or the like of the presentdisclosure, the inorganic semiconductor material preferably has anoxygen deficiency generation energy of 2.6 eV or more, and desirably 3.0eV or more. Alternatively, a higher value of the oxygen deficiencygeneration energy may lead to a case of a lower value of the carriermobility; therefore, in such a case, the inorganic semiconductormaterial preferably has an oxygen deficiency generation energy of 2.6 eVor more and 3.0 eV or less. Here, the oxygen deficiency generationenergy is energy required to generate oxygen deficiency; a higher valueof the oxygen deficiency generation energy makes it more difficult togenerate oxygen deficiency and makes it more difficult to incorporateoxygen atoms, oxygen molecules, or other atoms or molecules, which canbe said to bring stability. The oxygen deficiency generation energy isdeterminable, for example, from first principle calculation. It is to benoted that the inorganic semiconductor material layer contains aplurality of kinds of metal atoms, and thus “oxygen deficiencygeneration energy of metal atoms” refers to an average value of oxygendeficiency generation energies of the plurality of kinds of metal atomsin the inorganic semiconductor material.

A composition of the inorganic semiconductor material layer isdeterminable on the basis of, for example, ICP emission spectroscopy(high-frequency inductively coupled plasma atomic emission spectroscopy,ICP-AES) or X-ray photoelectron spectroscopy (X-ray PhotoelectronSpectroscopy, XPS). In the process of forming the inorganicsemiconductor material layer, an intrusion of hydrogen or other metal,or other impurities such as a metal compound can occur in some cases;however, the intrusion of the impurities may be acceptable as long asthe amount thereof is very small (e.g., 3% or less in molar fraction).

In the imaging element or the like of the present disclosure, a mode maybe adopted in which the inorganic semiconductor material layer isamorphous (e.g., amorphous having no local crystalline structures).Whether or not the inorganic semiconductor material layer is amorphousis determinable on the basis of X-ray diffraction analysis. However, theinorganic semiconductor material layer is not limited to beingamorphous, and may have a crystalline structure or a polycrystallinestructure.

FIG. 70 illustrates a configuration example of a stacked imaging element(stacked solid-state imaging device) as a comparative example. In theexample illustrated in FIG. 70, a third photoelectric conversion section343A and a second photoelectric conversion section 341A are stacked andformed in a semiconductor substrate 370. The third photoelectricconversion section 343A and the second photoelectric conversion section341A are photoelectric conversion sections of the second type, and areincluded in a third imaging element 343 and a second imaging element 341that are imaging elements of the second type. In addition, a firstphotoelectric conversion section 310A, which is a photoelectricconversion section of the first type, is disposed above thesemiconductor substrate 370 (specifically, above the second imagingelement 341). Here, the first photoelectric conversion section 310Aincludes a first electrode 321, a photoelectric conversion layer 323including an organic material, and a second electrode 322. The firstphotoelectric conversion section 310A is included in a first imagingelement 310 that is an imaging element of the first type. The secondphotoelectric conversion section 341A and the third photoelectricconversion section 343A photoelectrically convert, for example, bluelight and red light, respectively, owing to a difference in absorptioncoefficient. In addition, the first photoelectric conversion section310A photoelectrically converts, for example, green light.

The electric charge generated by the photoelectric conversion in thesecond photoelectric conversion section 341A and the third photoelectricconversion section 343A is temporarily accumulated in the secondphotoelectric conversion section 341A and the third photoelectricconversion section 343A. Thereafter, a vertical transistor (a gatesection 345 is illustrated) and a transfer transistor (a gate section346 is illustrated) transfer the electric charge to a second floatingdiffusion layer (Floating Diffusion) FD₂ and a third floating diffusionlayer FD₃, respectively, and the electric charge is further outputted toan external readout circuit (not illustrated). The transistors and thefloating diffusion layers FD₂ and FD₃ are also formed in thesemiconductor substrate 370.

The electric charge generated by the photoelectric conversion in thefirst photoelectric conversion section 310A is accumulated in a firstfloating diffusion layer FD₁ formed in the semiconductor substrate 370through a contact hole section 361 and a wiring layer 362. In addition,the first photoelectric conversion section 310A is also coupled to agate section 352 of an amplification transistor that converts theelectric charge amount into voltage through the contact hole section 361and the wiring layer 362. In addition, the first floating diffusionlayer FD₁ constitutes a portion of a reset transistor (a gate section351 is illustrated). Reference numeral 371 denotes an element separationregion. Reference numeral 372 denotes an oxide film formed on a surfaceof the semiconductor substrate 370. Reference numerals 376 and 381denote interlayer insulating layers. Reference numeral 383 denotes aprotection material layer. Reference numeral 314 denotes an on-chipmicrolens.

In the imaging element of the comparative example illustrated in FIG.70, the electric charge generated by the photoelectric conversion in thesecond photoelectric conversion section 341A and the third photoelectricconversion section 343A is once accumulated in the second photoelectricconversion section 341A and the third photoelectric conversion section343A, and is thereafter transferred to the second floating diffusionlayer FD₂ and the third floating diffusion layer FD₃. It is thereforepossible to completely deplete the second photoelectric conversionsection 341A and the third photoelectric conversion section 343A.However, the electric charge generated by photoelectric conversion inthe first photoelectric conversion section 310A is accumulated directlyin the first floating diffusion layer FD₁. It is therefore difficult tocompletely deplete the first photoelectric conversion section 310A. As aresult, kTC noise becomes greater and random noise deteriorates, whichmay possibly cause reduction in quality of captured images.

In the imaging element or the like of the present disclosure, asdescribed above, as long as the charge accumulation electrode isprovided that is disposed at a distance from the first electrode anddisposed to be opposed to the inorganic semiconductor material layerwith the insulating layer interposed therebetween, it is possible toaccumulate electric charge in the inorganic semiconductor material layer(in some cases, in the inorganic semiconductor material layer and thephotoelectric conversion layer) when the photoelectric conversionsection is irradiated with light and photoelectric conversion occurs inthe photoelectric conversion section. It is therefore possible tocompletely deplete the charge accumulation section and eliminate theelectric charge when exposure is started. As a result, it is possible tosuppress the occurrence of the phenomenon that the kTC noise becomesgreater and the random noise deteriorates to cause reduction in qualityof captured images. It is to be noted that, in the followingdescription, the inorganic semiconductor material layer, or theinorganic semiconductor material layer and the photoelectric conversionlayer, may be collectively referred to as an “inorganic semiconductormaterial layer or the like” in some cases.

The inorganic semiconductor material layer may have a single-layerconfiguration or a multilayer configuration. In addition, the inorganicsemiconductor material positioned above the charge accumulationelectrode and the inorganic semiconductor material positioned above thefirst electrode may be different from each other.

It is possible to form the inorganic semiconductor material layer on thebasis of, for example, a physical vapor deposition method (PVD method),specifically, a sputtering method. More specifically, examples of thesputtering method include one using a parallel flat plate sputteringdevice, a DC magnetron sputtering device or an RF sputtering device as asputtering device, an argon (Ar) gas as a process gas, and a desiredsintered body as a target. However, it is also possible to form theinorganic semiconductor material layer on the basis of a coating methodor the like, not being limited only to the PVD method such as thesputtering method or a vapor deposition method.

It is to be noted that it is possible to control the energy level of theinorganic semiconductor material layer by controlling the amount of anoxygen gas to be introduced (oxygen gas partial pressure) in forming theinorganic semiconductor material layer on the basis of a sputteringmethod. Specifically, it is preferred that the oxygen gas partialpressure at the time of formation on the basis of a sputtering method=(O₂ gas pressure)/(total pressure of Ar gas and O₂ gas) be 0.005 to0.10. Further, in the imaging element or the like of the presentdisclosure, a mode may be adopted in which the oxygen content of theinorganic semiconductor material layer is lower than the stoichiometricoxygen content. Here, the energy level of the inorganic semiconductormaterial layer is controllable on the basis of the oxygen content, andit is possible to allow the energy level to be deeper as the oxygencontent becomes lower than the stoichiometric oxygen content, namely, asoxygen deficiency becomes larger.

Further, in the imaging element or the like of the present disclosureincluding the various preferred modes and configurations describedabove, a mode may be adopted in which

the inorganic semiconductor material layer includes a first layer and asecond layer from side of the first electrode, and

ρ₁ ≥ 5.9  g/cm³  and ρ₁ − ρ₂ ≥ 0.1  g/cm³,

and preferably

ρ₁ ≥ 6.1  g/cm³  and ρ₁ − ρ₂ ≥ 0.2  g/cm³

are satisfied, where ρ₁ denotes an average film density of the firstlayer and ρ₂ denotes an average film density of the second layer in aportion extending for 3 nm, preferably 5 nm, or more preferably 10 nmfrom an interface between the first electrode and the inorganicsemiconductor material layer. It is to be noted that although the firstlayer is preferably as small as possible in thickness, a minimumthickness thereof is defined as 3 nm because it is necessary to preventformation of a discontinuous layer. In addition, a maximum thickness ofthe first layer is defined as 10 nm because an excessively largethickness degrades the characteristic of the inorganic semiconductormaterial layer. It is to be noted that, in this case, a mode may beadopted in which a composition of the first layer and a composition ofthe second layer are the same. Alternatively, a mode may be adopted inwhich

the inorganic semiconductor material layer includes a first layer and asecond layer,

a composition of the first layer and a composition of the second layerare the same, and

ρ₁ − ρ₂ ≥ 0.1  g/cm³,

and preferably

ρ₁ − ρ₂ ≥ 0.2  g/cm³

is satisfied, where ρ₁ denotes an average film density of the firstlayer and ρ₂ denotes an average film density of the second layer in aportion extending for 3 nm, preferably 5 nm, or more preferably 10 nmfrom an interface between the first electrode and the inorganicsemiconductor material layer.

Film densities are determinable on the basis of an XRR (X-RayReflectivity) method. Here, the XRR method is a method of determining afilm thickness and a film density of a sample by causing X-rays to beincident on a sample surface at an extremely shallow angle, measuring anintensity profile of the X-rays reflected in a mirror plane directionversus the incident angle, comparing the obtained intensity profile ofthe X-rays with simulation results, and optimizing the simulationparameters.

The imaging element of the present disclosure provided with such aninorganic semiconductor material layer including the first layer andsecond layer is obtainable by a method of manufacturing an imagingelement that includes

a photoelectric conversion section including a first electrode, aphotoelectric conversion layer including an organic material, and asecond electrode that are stacked, in which

an inorganic semiconductor material layer including the first layer andthe second layer, from the side of the first electrode, is formedbetween the first electrode and the photoelectric conversion layer,

the method including, after forming the first layer on the basis of asputtering method, forming the second layer on the basis of a sputteringmethod at input electric power lower than input electric power used informing the first layer.

As a result of various tests, it is appreciated that there is such arelationship that the average film density increases linearly as theinput electric power increases, between the input electric power and theaverage film density in forming the inorganic semiconductor materiallayer on the basis of the sputtering method. Here, in a case where theinput electric power is high, the orientations of the inorganicsemiconductor materials become uniform, and the inorganic semiconductormaterial layer becomes dense. In contrast, in a case where the inputelectric power is low, it is difficult for the orientations of theinorganic semiconductor materials to be uniform, and thus the inorganicsemiconductor material layer is considered to become rough.

Forming the inorganic semiconductor material layer including the firstlayer and the second layer from the side of the first electrode betweenthe first electrode and the photoelectric conversion layer and definingthe thickness of the first layer, the relationship between the averagefilm density ρ1 of the first layer and the average film density ρ₂ ofthe second layer in this manner eliminate the possibility of damaging anunderlayer when forming the first layer, thus making it possible toobtain an imaging element having superior characteristics.

Examples of the imaging element or the like of the present disclosureinclude a CCD element, a CMOS image sensor, a CIS (Contact ImageSensor), and a signal amplification image sensor of a CMD (ChargeModulation Device) type. The solid-state imaging devices according tothe first and second aspects of the present disclosure and thesolid-state imaging devices of first and second configurations describedlater are able to be included in, for example, a digital still camera, avideo camera, a camcorder, a monitoring camera, an on-vehicle camera, asmartphone camera, a user interface camera for games, and a biometricauthentication camera.

Example 1

Example 1 relates to the imaging elements of the present disclosure, thestacked imaging element of the present disclosure, the solid-stateimaging device according to the second aspect of the present disclosure,and the method of manufacturing the imaging element of the presentdisclosure. FIG. 1 is a schematic partial cross-sectional view of theimaging element and the stacked imaging element (hereinafter simplyreferred to as an “imaging element”) of Example 1. FIGS. 2 and 3 areequivalent circuit diagrams of the imaging element of Example 1. FIG. 4is a schematic layout diagram of the first electrode and the chargeaccumulation electrode included in the photoelectric conversion section,and transistors included in the control section of the imaging elementof Example 1. FIG. 5 schematically illustrates a state of potential ateach part during operation of the imaging element of Example 1. FIG. 6Ais an equivalent circuit diagram for describing each part of the imagingelement of Example 1. FIG. 7 is a schematic layout diagram of the firstelectrode and the charge accumulation electrode included in thephotoelectric conversion section of the imaging element of Example 1.FIG. 8 is a schematic transparent perspective view of the firstelectrode, the charge accumulation electrode, the second electrode, anda contact hole section. Further, FIG. 68 illustrates a conceptualdiagram of the solid-state imaging device of Example 1.

It is to be noted that, FIGS. 37, 43, 46A, 46B, 47A, and 47B omitillustration of a photoelectric conversion layer 23A and an inorganicsemiconductor material layer 23B, and the photoelectric conversion layer23A and the inorganic semiconductor material layer 23B are collectivelyrepresented by a photoelectric conversion stack 23. In addition, InFIGS. 16, 25, 28, 37, 43, 46A, 46B, 47A, 47B, 66, and 67, variousconstituent elements of the imaging element positioned below aninterlayer insulating layer 81 are collectively denoted by Referencenumeral 13 for the sake of convenience in order to simplify thedrawings.

The imaging element of Example 1 includes a photoelectric conversionsection including a first electrode 21, the photoelectric conversionlayer 23A including an organic material, and a second electrode 22 thatare stacked, and the inorganic semiconductor material layer 23B isformed between the first electrode 21 and the photoelectric conversionlayer 23A.

The photoelectric conversion layer 23A includes C60 having a thicknessof 0.1 μm.

The stacked imaging element of Example 1 includes at least one imagingelement of Example 1. In addition, the solid-state imaging device ofExample 1 includes a plurality of stacked imaging elements of Example 1.Then, the solid-state imaging device of Example 1 is to be included in,for example, a digital still camera, a video camera, a camcorder, amonitoring camera, an on-vehicle camera (vehicle-mounted camera), asmartphone camera, a user interface camera for games, and a biometricauthentication camera.

In the imaging element of Example 1, the valueΔEN(=EN_(anion)−EN_(cation)) is less than 1.695, and preferably 1.624 orless, which results from subtracting the average value EN_(cation) ofelectronegativities of the cationic species included in the inorganicsemiconductor material layer 23B from the average value EN_(anion) ofelectronegativities of the anionic species included in the inorganicsemiconductor material layer 23B.

Here, when the inorganic semiconductor material layer 23B is representedby (A¹ _(a1)A² _(a2)A³ _(a3) . . . A^(M) _(aM))(B¹ _(b1)B² _(b2)B³ _(b3). . . B^(N) _(bN)) [where A¹, A², A³, . . . , and A^(M) are cationicspecies, B¹, B², B³, . . . , and B^(N) are anionic species, and a1, a2,a3, . . . , and aM, and b1, b2, b3, . . . , and bN are valuescorresponding to atomic percentages, with the total thereof being 1.00],

${EN_{anion}} = \frac{\left( {{B\; 1 \times b\; 1} + {B\; 2 \times b\; 2} + {B\; 3 \times b\; 3\mspace{14mu}\ldots} + {B\; N \times b\; N}} \right)}{\left( {{b\; 1} + {b\; 2} + {b\; 3\mspace{14mu}\ldots} + {b\; N}} \right)}$${EN_{cation}} = \frac{\left( {{A\; 1 \times a\; 1} + {A\; 2 \times a\; 2} + {A\; 3 \times a\; 3\mspace{14mu}\ldots} + {A\; M \times a\; M}} \right)}{\left( {{a\; 1} + {a\; 2} + {a\; 3\mspace{14mu}\ldots} + {a\; M}} \right)}$

hold true, where B1, B2, B3, . . . , and BN are electronegativities ofthe anionic species B¹, B², B³ . . . , and B^(N), and A1, A2, A3, . . ., and A^(M) are electronegativities of the cationic species A¹, A², A³ .. . , and A^(M).

The cationic species include at least one type of cationic speciesselected from the group consisting of Zn, Ga, Ge, Cd, In, Al, Ti, B, Si,Sn, Hg, Tl, and Pb, and the anionic species include at least one type ofanionic species selected from the group consisting of O, N, S, and F.Specifically, for example, a configuration (In_(a1)Ga_(a2)Sn_(a3)O_(b1))may be adopted in which the cationic species include Ga, In, and Sn, andthe anionic species include O. Alternatively, a configuration (A¹_(a1)Zn_(a2)Sn_(a3)O_(b1)) may be adopted in which the cationic speciesinclude Zn, Al, and Sn, and the anionic species include O.

Electric charge generated in the photoelectric conversion layer 23Amoves to the first electrode 21 via the inorganic semiconductor materiallayer 23B; in this case, the electric charge is an electron. Theinorganic semiconductor material layer 23B has a thickness of 1×10⁻⁸ mto 1.5×10⁻⁷ m. The inorganic semiconductor material layer 23B has acarrier mobility of 10 cm²/V·s or more; the inorganic semiconductormaterial layer 23B has a carrier density (carrier concentration) of1×10¹⁶/cm³ or less; and the inorganic semiconductor material layer 23Bis amorphous. The inorganic semiconductor material has an optical gap of2.8 eV or more and 3.2 eV or less, and preferably 3.0 eV or more and 3.2eV or less; and the inorganic semiconductor material has an oxygendeficiency generation energy of 2.6 eV or more, and desirably 3.0 eV ormore.

E₁ ≥ E₀

desirably,

E₁ − E₀ ≥ 0.1  (eV)

and more desirably,

E₁ − E₀ > 0.1  (eV)

is satisfied, where E₀ denotes a LUMO value of a material included inthe photoelectric conversion layer 23A, and E₁ denotes a minimum energyvalue of a conduction band of an inorganic semiconductor materialincluded in the inorganic semiconductor material layer 23B.

The photoelectric conversion section further includes an insulatinglayer 82, and a charge accumulation electrode 24 disposed at a distancefrom the first electrode 21 and disposed to be opposed to the inorganicsemiconductor material layer 23B with the insulating layer 82 interposedtherebetween. Specifically, the inorganic semiconductor material layer23B includes a region in contact with the first electrode 21, a regionthat is in contact with the insulating layer 82 and below which thecharge accumulation electrode 24 is not present, and a region that is incontact with the insulating layer 82 and below which the chargeaccumulation electrode 24 is present. Then, light enters from the secondelectrode 22. The surface roughness Ra of a surface of the inorganicsemiconductor material layer 23B at an interface between thephotoelectric conversion layer 23A and the inorganic semiconductormaterial layer 23B is 1.5 nm or less, and the root mean square roughnessRq of the surface of the inorganic semiconductor material layer 23B is2.5 nm or less. The surface roughness Ra of a surface of the chargeaccumulation electrode 24 is 1.5 nm or less, and the root mean squareroughness Rq of the surface of the charge accumulation electrode 24 is2.5 nm or less.

The inorganic semiconductor material layer 23B is formed on the basis ofa sputtering method, a vacuum deposition method, or the like, forexample, in a state of an amorphous thin film. As illustrated in (A) ofFIG. 71, in a state immediately after film formation (As depo), thereare a large amount of unstable dangling bonds in the inorganicsemiconductor material layer 23B, and thus the inorganic semiconductormaterial layer 23B exhibits no electric conductivity. Therefore,applying an annealing process to the inorganic semiconductor materiallayer 23B in an atmosphere containing water vapor (in an atmosphericatmosphere, etc.) causes hydrogen from the water vapor to be diffusedand infiltrated to the inside of the inorganic semiconductor materiallayer 23B as indicated by the formula below, thus making it possible toaccelerate structural changes, eliminate the unstable dangling bonds(see (B) of FIG. 71), and convert them into stable metal-oxygen bonds(see (C) of FIG. 71 and (D) of FIG. 71). This makes it possible toimpart favorable characteristics to the inorganic semiconductor materiallayer 23B. In order to thus diffuse and infiltrate the hydrogen requiredto stabilize an atomic structure of the inorganic semiconductor materiallayer 23B into an accumulation layer, a temperature higher than 250° C.is necessary, for example, in InGaZnO₄.

H₂O→H⁺+OH⁻

In addition, as illustrated in (E) of FIG. 71, (F) of FIG. 71, (G) ofFIG. 71, and (H) of FIG. 71, the diffusion and infiltration of hydrogenalso accelerate formation of metal-hydrogen bonds. In the metal-hydrogenbonds, hydrogen serves as a hydride ion (H⁻), which is effective instabilizing and deactivating excess carriers. This leads to a reductionin the carrier density in the inorganic semiconductor material layer23B, which enables an increase in the amount of electric chargeaccumulated in the inorganic semiconductor material layer 23B. On thecontrary, suppose a case where a material included in the inorganicsemiconductor material layer 23B is used for a channel structure part ofa thin film transistors (TFT), a carrier density of about 10¹⁹/cm³ ormore is required unlike the case where the inorganic semiconductormaterial layer 23B is used for the imaging element. Therefore, such anannealing process is a suitable for the manufacture of the imagingelement, rather than a process for the manufacture of the thin filmtransistor.

In addition, the annealing process at 250° C. or lower enablesprevention of damage occurrence to a drive circuit for driving theimaging element or to a semiconductor substrate and enables improvementin a degree of freedom of process such as enabling the use of a plasticsubstrate as the substrate.

The present disclosure thus provides a criterion for selecting amaterial that enables a low-temperature annealing process, such as anannealing process at 250° C. or lower suitable for the inorganicsemiconductor material layer 23B. The selection criterion is used toallow the inorganic semiconductor material layer 23B to have a highcovalent bonding property; the ΔEN, which is an index thereof, may becalculated from a composition of the material of the inorganicsemiconductor material layer 23B. Specifically, in a case where thecomposition of the material included in the inorganic semiconductormaterial layer 23B is In_(a1)Ga_(a2)Zn_(a3)O_(b1)N_(b2), the followinghold true:

electronegativity  of  indium  (In) = 1.78electronegativity  of  gallium  (Ga) = 1.81electronegativity  of  zinc  (Zn) = 1.65electronegativity  of  oxygen  (O) = 3.44electronegativity  of  nitrogen  (N) = 3.04 and${EN_{anion}} = \frac{\left( {{{3.4}4 \times b\; 1} + {3.04 \times b2}} \right)}{\left( {{b\; 1} + {b\; 2}} \right)}$${EN_{cation}} = {\frac{\left( {{1.78 \times a1} + {{1.8}1 \times a2} + {1.65 \times a3}} \right)}{\left( {{a\; 1} + {a\; 2} + {a\; 3}} \right)}.}$

The electronegativity of each element is set forth, for example, in A.L. Allred, Journal of Inorganic and Nuclear Chemisty, vol. 17, 1961, p215. In addition, the ΔEN, which is an index of a covalent bondingproperty, is represented by:

ΔEN = EN_(anion) − EN_(cation).

Here, a smaller value of the ΔEN indicates a higher covalent bondingproperty.

The electronegativity is defined as force that attracts a covalentelectron pair. For example, a bond between an oxygen (O) atom having ahigh electronegativity of 3.44 and a zinc (Zn) atom having a relativelylow electronegativity of 1.65 exhibits a ΔEN value of 1.79 (=3.44−1.65).The zinc (Zn) atom has weak force to attract a covalent electron pair,whereas the oxygen (O) atom has strong force to attract. Accordingly,the covalent electron pair is positioned on side of the oxygen atom, andthus the oxygen atom is largely negatively charged, whereas the zincatom is positively charged. As a result, bonds are formed byelectrostatic interactions. This is a feature of “ionic bond”, and ZnOhas a high ionic bonding property.

Meanwhile, a bond between an oxygen (O) atom having a highelectronegativity of 3.44 and a tin (Sn) atom having a relatively highelectronegativity of 1.96 exhibits a ΔEN value of 1.48 (=3.44−1.48),which is a value lower than the ΔEN value of ZnO. That is, covalentelectron pairs mediating cation-anion bonding in the inorganicsemiconductor material layer 23B is biased toward the middle of the bondas compared with ZnO, and the negative charge of the oxygen atom and thepositive charge of the tin atom are small (close to neutral than both ofthem). This case is referred to as having a high covalent bondingproperty. Therefore, a material having a high covalent bonding propertymay be defined as having a small ΔEN. Description is given later, on thebasis of Examples, of a range to be taken by the ΔEN in order to allowan annealing process to be performed at a low temperature and in anatmospheric atmosphere in the inorganic semiconductor material layer23B.

Next, description is given, with reference to FIG. 72, of the reason whyhydrogen is more easily diffused and infiltrated to the inorganicsemiconductor material layer 23B in the case of a high covalent bondingproperty. FIG. 72 schematically illustrates electric distributions(electrostatic potentials) of a material having a high covalent bondingproperty and a material having a high ionic bonding property. Asillustrated in (A) of FIG. 72, in a material having a higher covalentbonding property, the covalent electron pair exists between a metalelement M1 and an oxygen atom O, thus causing polarization to be smalland undulation of the electrostatic potential to be also small. Hydrogenis diffused in a state of H⁺ protons; thus, in a case where theundulation of the electrostatic potential is small, hydrogen is easilydiffused in the inorganic semiconductor material layer 23B. On thecontrary, as illustrated in (B) of FIG. 72, in a material having a highionic bonding property, the covalent electron pair is biased toward theside of the oxygen atom between a metal element M2 and an oxygen atom O,thus causing undulation of the electrostatic potential to be large, andhigh energy is required for hydrogen to be diffused. Accordingly, thehigher covalent bonding property (i.e., smaller ΔEN value) enableshydrogen to be diffused despite a low annealing temperature.

Further, unlike the TFT, the inorganic semiconductor material layer 23Bin the imaging element needs to have reduced carrier density. For thisreason, it is necessary to increase the number of hydrogen (H⁻; hydrideion) to be directly bonded to a cation. Unlike a proton (H⁺), thehydride ion (H⁻) is an ion having two electrons and being negativelycharged. When being diffused by an annealing process in the atmosphericatmosphere, hydrogen exists mainly in a state of proton (H⁺), butdeactivates carriers (i.e., electrons existing in a conduction band) tobecome the hydride ion (H⁻), thus enabling a decrease in the carrierdensity in the conduction band. This effect leads to deterioration ofthe characteristics of a TFT due to lowered carrier mobility in the TFT,but gives a desirable effect of lowered carrier density in the inorganicsemiconductor material layer 23B.

Here, a cation likely to generate the hydride ion is an element having“relatively high electronegativity among metal elements”. That is, as anindex, it is sufficient to select an element having high EN_(cation),and thus to consequently lower the ΔEN. This is equivalent to theabove-described index of the hydrogen diffusion. Accordingly, thematerial-design guideline for lowering the ΔEN is a suitable guidelinefor simultaneously enhancing the two effects of the hydrogen diffusionand the generation of the hydride ion (H⁻) that are necessary for theinorganic semiconductor material layer 23B.

Description is given of the reason why an element having relatively highelectronegativity among metal elements is more likely to generate thehydride ion (H⁻), in accordance with the basic theory of chemistry, suchas the basic theory of quantum chemistry and HSAB (Hard and Soft, Acidsand Basis). A metal element M having an unoccupied orbital on low-energyside is likely to form a bond of a covalent bonding property when beingbonded to an anion, and has high electronegativity (see (A) of FIG. 73).On the contrary, a metal element having an unoccupied orbital onhigh-energy side is likely to form a bond of an ionic bonding propertywhen being bonded to an anion, and has low electronegativity (see (B) ofFIG. 73). It is to be noted that, in FIG. 73, “H-s” indicates an sorbital of hydrogen. For example, an alkali metal or an alkaline earthmetal such as Li or Mg is very likely to form an ionic bond. Meanwhile,Si or Tn is likely to form a covalent bond. In addition, there are alsoions, in anions, that are likely to form covalent bonds and ions thatare likely to form ionic bonds. An anion having a stable occupiedorbital such as fluorine (F) or chlorine (Cl) is likely to form an ionicbond, and has high electronegativity. Nitrogen (N) and sulfur (S) arelikely to form a covalent bond, and has low electronegativity. An anionthat is likely to form a covalent bond (an ion having lowerelectronegativity among anions) and a cation that is likely to form acovalent bond (an ion having relatively high electronegativity amongcations) have favorable compatibility, and are likely to form a strongcovalent bond. The anion that is likely to form a covalent bond isreferred to as a “soft” acid, and a cation that is likely to form acovalent bond is referred to as a “soft” base.

Here, the hydride ion is an anion in a category of a very high covalentbonding property, i.e., the very “soft” acid, and thus has favorablecompatibility with the “soft” cation. The “soft” cation is the samemeaning as that of a metal ion having high electronegativity, and thusselection of a metal element or a composition that makes EN_(cation)higher enables an increase in hydride ions in the inorganicsemiconductor material layer 23B. As described above, the hydride ionhas an effect of stabilizing and deactivating carrier electric charge(electron), and thus is able to contribute to achieving physicalproperties suitable for the inorganic semiconductor material layer 23Bhaving lower carrier density.

In addition, it is desirable for the inorganic semiconductor materiallayer 23B to have high carrier mobility because of necessity oftransferring signal charge within a limited period of time. For thispurpose, it is preferred to use an inorganic semiconductor material (oran inorganic oxide semiconductor material) to be included in theinorganic semiconductor material layer 23B. Among those, it is preferredto use a metal element having a closed-shell d orbital, for example.Specific examples of the metal element having the closed-shell d orbitalinclude Cu, Ag, Au, Zn, Ga, Ge, Cd, In, Sn, Hg, Tl, and Pb.

Thin-film transistors (TFTs) of samples for evaluation (Examples 1A and1B and Comparative Example 1) were prepared experimentally on the basisof various inorganic semiconductor materials. Specifically, the samplesfor evaluation were back-gate type TFTs in which an n-Si substrate wasused as a gate electrode, an insulating film including SiO₂ and having athickness of 150 nm was formed as a gate insulating film on thesubstrate, an inorganic semiconductor material layer (thickness: 60 nm)was formed on the insulating film, and a source electrode and a drainelectrode were formed on the inorganic semiconductor material layer.After the preparation of the samples for evaluation, the inorganicsemiconductor material layers were subjected to an anneal process (ananneal process in an atmospheric atmosphere containing water vapor) at250° C. for 2 hours. Results of determination of subthreshold values(unit: volt/dec.) of the resulting samples for evaluation are listed inTable 1 below. It is to be noted that the subthreshold values (SSvalues) are determined by [d (V_(GS))/{d(log₁₀(ID)}], and it can be saidthat a smaller value is superior in the switching property. Further, (A)of FIG. 74 (Example 1A), (B) of FIG. 74 (Example 1B), and (C) of FIG. 74(Comparative Example 1) illustrate results of evaluation of arelationship between VGS and ID in the TFT, as TFT characteristics. Notethat, in Example 1B, the following hold true:

a1 = 0.04  or  less a 2 = 0.5  to  0.7 a 3 = 0.3  to  0.5b 1 = d = 1.5 × a 1 + a 2 + a 3.

TABLE 1 ΔEN SS Value Example 1A InGaSnO 1.605 0.10 Example 1BAl_(al)Zn_(a2)Sn_(a3)O_(b1) 1.624 0.30 Comparative example 1In_(1.0)Ga_(1.0)Zn_(1.0)O_(4.0) 1.695 not modulated

Here, as a value of the rising part of the TFT characteristics (VON) isshifted to negative side, the carrier density becomes larger. Therefore,it is obvious from (A), (B), and (C) of FIG. 74 that the carrier densityis the lowest in Example 1A, and becomes higher in the order of Example1B and Comparative Example 1. In Comparative Example 1, the carrierdensity is too high, and thus the carrier density is not zero in aregion illustrated in (C) of FIG. 74 even when the voltage VGS isapplied to the negative side, causing a current to continue to flow.

The characteristics of Comparative Example 1 do not enable accumulationof electric charge in the inorganic semiconductor material layer 23B,and thus using as the inorganic semiconductor material layer 23B is notpossible. In contrast, in Example 1B, ΔEN==1.624 holds true; the TFT wasmodulated, and the SS value was also 0.30 volts/dec. That is, it ispossible to accumulate electric charge in the inorganic semiconductormaterial layer 23B, and thus using as the inorganic semiconductormaterial layer 23B is possible. Further, in Example 1A in whichΔEN=1.605 holds true, the SS value is 0.10 volts/dec., thus enablingfaster switching. In Example 1A, it is possible to acquire animage/picture with less residual image as compared with Example 1B.

For reference, FIG. 75A illustrates results of evaluation of arelationship between VGS and ID in the TFT, as TFT characteristics, whensetting an annealing temperature from 250° C. through 280° C. to 350°C., and FIG. 75B illustrates results of determination of aryltemperature and hydrogen concentration, in Comparative Example 1 usingIn_(1.0)Ga_(1.0)Zn_(1.0)O_(4.0) (IGZO). It is to be noted that, in FIG.75A, “A” is data at an annealing temperature of 250° C., “B” is data atan annealing temperature of 280° C., and “C” is data at an annealingtemperature of 350° C.; it was appreciated that a higher annealingtemperature causes the TFT to operates at a lower value of VGS. Inaddition, it was appreciated that a higher annealing temperature causesthe hydrogen concentration to be higher.

As described above, the method of manufacturing the imaging element inExample 1 is a method of manufacturing an imaging element includingsequentially forming, on an underlayer (specifically, insulating layer82) in which the first electrode 21 is formed, the inorganicsemiconductor material layer 23B, the photoelectric conversion layer 23Aincluding an organic material, and the second electrode 22. Then, afterthe formation of the inorganic semiconductor material layer 23B, anannealing process is applied at 250° C. or less, preferably at 150° C.or more in an atmosphere containing water vapor. Specifically, forexample, it is sufficient to apply an annealing process by means of anatmospheric atmosphere containing water vapor after the formation of theinorganic semiconductor material layer 23B and before the formation ofthe photoelectric conversion layer 23A.

In a case where In_(a1)Ga_(a2)Sn_(a3)O_(b1) is included in the inorganicsemiconductor material layer 23B, it is preferred to satisfy a1>a2 anda1>a3. In this case, it is preferred to satisfy a1>a2>a3, or it ispreferred to satisfy a1>a3>a2, and it is more preferred to satisfya1>a2>a3. Alternatively, in these cases, a mode may be adopted in which:

a 1 + a 2 + a 3 + b 1 = 1.00 0.4 < a 1/(a 1 + a 2 + a 3) < 0.50.3 < a2/(a 1 + a 2 + a 3) < 0.4 0.2 < a3/(a 1 + a 2 + a 3) < 0.3

are satisfied. Alternatively, a mode may be adopted in which:

a 1 + a 2 + a 3 + b 1 = 1.00 0.30 < a 1/(a 1 + a 2 + a 3) < 0.550.20 < a2/(a 1 + a 2 + a 3) < 0.35 0.25 < a3/(a 1 + a 2 + a 3) < 0.45

are satisfied.

In addition, in a case where Al_(a1)Zn_(a2)Sn_(a3)O_(b1) is included inthe inorganic semiconductor material layer 23B, satisfying:

$\begin{matrix}{{{0.8}8 \times \left( {{a3} - {0.3}} \right)} > {{0.1}2 \times a1}} & (1)\end{matrix}$

where a1+a2+a3=1.00 as well as a1>0, a2>0, and a3>0 hold true (the sameapplies to the following) makes it possible to satisfy a definition ofΔEN being less than 1.695. Here, in FIG. 76A, a solid line “A” indicatesa straight line satisfying:

0.88 × (a3 − 0.3) = 0.12 × a1.

A region satisfying expression (1) is a region surrounded by a point p₁,a point p₂, and a point p₃ of FIG. 76A.

It is to be noted that, a simulation is performed to determineelectronic state density, or first principle calculation is performed,in Al_(a1)Zn_(a2)Sn_(a3)O_(b1) in which values of the composition (a1,a2, and a3) are changed variously, to thereby determine valuescorrelated with values of the optical gap, the carrier mobility, and theoxygen deficiency generation energy. On the basis of the determinedvalues, the values of (a1, a2, and a3) are linearly determined, fromwhich the optical gap, the oxygen deficiency generation energy, and thecarrier mobility of desired values are obtained. This makes it possibleto obtain later-described expression (2), expression (2′), expressions(3-1) and (3-2), expressions (3-1′) and (3-2′), expressions (3-1),(3-2), (3-1″) and (3-2″), and expression (4).

Here, in a case where Al_(a1)Zn_(a2)Sn_(a3)O_(b1) is to be included inthe inorganic semiconductor material layer 23B, an optical gap of aninorganic semiconductor material (simply referred to as the “inorganicsemiconductor material” in some cases) included in the inorganicsemiconductor material layer 23B is determined mainly by a ratio betweenaluminum atoms and tin atoms (proportion of the number of atoms) in thecomposition of the inorganic semiconductor material; as the ratio ofaluminum atoms becomes higher, the value of the optical gap becomeslarger. In order for the inorganic semiconductor material layer to betransparent in a visible-light range, the optical gap is required to be2.8 eV or more. Meanwhile, in order for the inorganic semiconductormaterial layer to reliably receive electric charge generated in thephotoelectric conversion layer, the level of a conduction band of theinorganic semiconductor material is required to be deeper than the levelof a conduction band of a material included in the photoelectricconversion layer; for that purpose, the inorganic semiconductor materialpreferably has an optical gap of, for example, 3.2 eV or less. Inaddition, the likelihood of occurrence of oxygen deficiency (in otherwords, low value in the oxygen deficiency generation energy) of theinorganic semiconductor material is determined mainly by the ratiobetween aluminum atoms and tin atoms (proportion of atomic numbers) inthe composition of the inorganic semiconductor material; as the ratio oftin atoms becomes higher, the oxygen deficiency of the inorganicsemiconductor material is more likely to occur, resulting in crystaldefect being more likely to occur. The inorganic semiconductor materiallayer is provided to accumulate electric charge generated in thephotoelectric conversion layer and to transfer the electric charge to afirst electrode, and thus generation of carriers due to the crystaldefect and the oxygen deficiency of the inorganic semiconductor materiallayer leads to an increase in carrier density and to an increase in adark current, thus deteriorating an S/N ratio of the imaging element.Further, the inorganic semiconductor material layer is provided totransfer electric charge generated in the photoelectric conversion layerto the first electrode; therefore, when a transfer rate is slow, ittakes time to read out a signal from the imaging element, thus making ithardly possible to obtain an appropriate frame rate required by thesolid-state imaging device. In order to increase the transfer rate,carrier mobility of the inorganic semiconductor material layer, i.e.,field mobility needs to be increased. As for a relationship between theratio between aluminum atoms and zinc atoms (proportion of the number ofatoms) in the composition of the inorganic semiconductor material andthe carrier mobility, as the ratio of zinc atoms becomes higher, thevalue of the carrier mobility becomes lower. As for a relationshipbetween the ratio between tin atoms and zinc atoms (proportion of thenumber of atoms) in the composition of the inorganic semiconductormaterial and the carrier mobility, as the ratio of zinc atoms becomeshigher, the value of the carrier mobility becomes lower.

In addition, adopting a mode in which:

$\begin{matrix}{{{0.3}6 \times \left( {{a3} - {{0.6}2}} \right)} \leq {{0.6}4 \times a\; 1} \leq {0.36 \times a3}} & (2)\end{matrix}$

is satisfied enables the inorganic semiconductor material to achieve theoptical gap of 2.8 eV or more and 3.2 eV or less. Employing the modeenables the inorganic semiconductor material layer to be a transparentlayer with respect to incident light, and eliminates the possibility ofcausing a barrier to movement of electric charge from the photoelectricconversion layer to the inorganic semiconductor material layer. Here, inFIG. 76B, a dotted line “B” indicates a straight line satisfying:

0.36 × (a3 − 0.62) = 0.64 × a 1,

and a dotted line “C” indicates a straight line satisfying:

64 × a 1 = 0.36 × a3.

Alternatively, a mode may be adopted in which the inorganicsemiconductor material has an optical gap of 3.0 eV or more and 3.2 eVor less to allow the inorganic semiconductor material layer to be alayer transparent to incident light in a still wider wavelength range.In addition, in the imaging element or the like of the presentdisclosure including such a preferred mode, adopting a mode in which:

$\begin{matrix}{{0.36 \times \left( {{a3} - {{0.2}5}} \right)} \leq {{0.6}4 \times a\; 1} \leq {0.36 \times a3}} & \left( 2^{\prime} \right)\end{matrix}$

is satisfied enables the inorganic semiconductor material to achieve theoptical gap of 3.0 eV or more and 3.2 eV or less.

In addition, adopting a mode in which:

$\begin{matrix}{{a3} \leq {0{.67}}} & \text{(3-1)} \\{{and}\mspace{14mu}} & \; \\{{0.60 \times \left( {{a3} - {{0.6}1}} \right)} \leq {{0.4}0 \times a\; 1}} & \text{(3-2)}\end{matrix}$

are satisfied enables the inorganic semiconductor material to achievethe oxygen deficiency generation energy of 2.6 eV or more. Here, in FIG.76B, a dotted line “D₁” indicates a straight line satisfying:

a3 = 0.67,

and a dotted line “D₂” indicates a straight line satisfying:

0.60 × (a3 − 0.61) = 0.40 × a 1.

Alternatively, a mode may be adopted in which the inorganicsemiconductor material has an oxygen deficiency generation energy of 3.0eV or more. In addition, in the imaging element or the like of thepresent disclosure including such a preferred mode, adopting a mode inwhich:

$\begin{matrix}{{a3} \leq {0{.53}}} & {\text{(3-}\left. 1^{\prime} \right)} \\{and} & \; \\{{0.35 \times \left( {{a3} - {{0.3}2}} \right)} \leq {{0.6}5 \times a\; 1}} & {\text{(3-}\left. 2^{\prime} \right)}\end{matrix}$

are satisfied enables the inorganic semiconductor material to achievethe oxygen deficiency generation energy of 3.0 eV or more. Here, in FIG.76B, a dotted line “E₁” indicates a straight line satisfying:

a3 = 0.53,

and a dotted line “E₂” indicates a straight line satisfying:

0.35 × (a3 − 0.32) = 0.65 × a 1.

Alternatively, a higher value of the oxygen deficiency generation energymay lead to a case of a lower value of the carrier mobility; in such acase, a mode may be adopted in which the inorganic semiconductormaterial has an oxygen deficiency generation energy of 2.6 eV or moreand 3.0 eV or less. In addition, in the imaging element or the like ofthe present disclosure including such a preferred mode, adopting a modein which:

$\begin{matrix}{{a3} \leq 0.67} & \text{(3-1)} \\{{0.60 \times \left( {{a\; 3} - 0.61} \right)} \leq {0.40 \times a\; 1}} & \text{(3-2)} \\{{a\; 3} \geq 0.53} & {\text{(3-}\left. 1^{''} \right)} \\{{and}\mspace{14mu}} & \; \\{{0.35 \times \left( {{a3} - {{0.3}2}} \right)} \geq {{0.6}5 \times a\; 1}} & {\text{(3-}\left. 2^{''} \right)}\end{matrix}$

are satisfied enables the inorganic semiconductor material to achievethe oxygen deficiency generation energy of 2.6 eV or more and 3.0 eV orless.

Further, adopting a mode in which:

$\begin{matrix}{{a\; 3} \geq {{a\; 2} - 0.54}} & (4)\end{matrix}$

is satisfied makes it possible to impart, to the inorganic semiconductormaterial layer, high carrier mobility, specifically, a high carriermobility of 10 cm²/V·s or more. As a result, it is possible to quicklymove electric charge accumulated in the inorganic semiconductor materiallayer to the first electrode. Here, in FIG. 76B, a dotted line “F”indicates a straight line satisfying:

a3 = a2 − 0.54.

In addition, the inorganic semiconductor material layer preferably has acarrier density of 1×10¹⁶/cm³ or less, which enables an increase in theamount of electric charge accumulated in the inorganic semiconductormaterial layer.

Here, a region of (a1, a2, and a3) satisfying expression (1), expression(2), expression (3-1), expression (3-2), and expression (4) illustratedin FIG. 76B is a region surrounded by a point p₂, a point p₄, a pointp₅, a point p₆, a point p₇, and a point p₈.

Alternately, when the composition of the inorganic semiconductormaterial included in the inorganic semiconductor material layer isrepresented by M_(a1)N_(a2)Sn_(a3)O_(b1) (where M denotes an aluminumatom, and N denotes a gallium atom or a zinc atom, or a gallium atom anda zinc atom), it is preferred to satisfy:

a 1 + a 3 + a 2 = 1.00 0.01 ≤ a1 ≤ 0.04 and   a 3 < a 2,

and it is preferred to further satisfy a1<a3<a2.

In the imaging element of Example 1, defining the ΔEN as being less than1.695 makes it is possible to form the inorganic semiconductor materiallayer under an annealing condition at a low temperature. As a result, itis possible to suppress occurrence of damage to other layers included inthe imaging element, thus making it possible to achieve improvement inyield and improvement in durability of the imaging element, and tofurther decrease the SS value, thereby enabling high-speed operation.Therefore, it is possible to achieve an imaging element that allows fora picture/image with less residual image. In addition, it is possible toobtain an inorganic semiconductor material layer having superior balanceof characteristics such as the carrier mobility, the carrier density,the SS value, and the transparency with respect to incident light.Further, it is possible to achieve, in a well-balanced manner,optimization of the carrier density of the inorganic semiconductormaterial layer (optimization of a degree of depletion of the inorganicsemiconductor material layer), high carrier mobility of an inorganicsemiconductor material layer included in the inorganic semiconductormaterial layer, control of the minimum energy value E₁ of the conductionband of the inorganic semiconductor material included in the inorganicsemiconductor material layer, and suppression of generation of theoxygen deficiency in the inorganic semiconductor material layer.Therefore, despite the simple configuration and structure, it ispossible to provide an imaging element, a stacked imaging element, and asolid-state imaging device having less loss of incident light and beingsuperior in transfer characteristic for the electric charge accumulatedin the photoelectric conversion layer. Moreover, the inorganicsemiconductor material layer is stable with respect to a manufacturingprocess of the imaging element after formation of the inorganicsemiconductor material layer, and it is also possible to suppress ageddeterioration of the imaging element, the stacked imaging element, andthe solid-state imaging device. In addition, the energy level E₁ of theconduction band of the inorganic semiconductor material is formed to bedeeper than the LUMO value E₀ of the material included in thephotoelectric conversion layer. As a result, an energy barrier betweenthe inorganic semiconductor material layer and the adjacentphotoelectric conversion layer is reduced, and it is thus possible toachieve reliable movement of electric charge from the photoelectricconversion layer to the inorganic semiconductor material layer. Also,the escape of holes is suppressed. In addition, because thephotoelectric conversion section has a two-layer structure of theinorganic semiconductor material layer and the photoelectric conversionlayer, it is possible to prevent recombination during chargeaccumulation, and it is possible to further increase the efficiency oftransfer of the electric charge accumulated in the photoelectricconversion layer to the first electrode. Further, it is possible totemporarily hold the electric charge generated in the photoelectricconversion layer to thereby control the timing of transfer and the like.It is also possible to suppress the generation of a dark current.Moreover, in the method of manufacturing the imaging element of Example1, the annealing process is applied at 250° C. or less in an atmospherecontaining water vapor after the formation of the inorganicsemiconductor material layer, thus making it possible to suppressoccurrence of damage to other layers included in the imaging element,and to achieve improvement in the yield and improvement in durability ofthe imaging element. In addition, it is possible to manufacture animaging element having superior characteristics.

Furthermore, even under the annealing condition at a low temperaturesuch as 250° C., it is possible to achieve characteristics thatobviously exceed IGZO. In addition, in the present disclosure,accelerating the diffusion of hydrogen and increasing the covalentbonding property make it possible to increase the rate of direct bondingof H as an H⁻ ion to a metal element. As a result, it is possible toreduce the carrier density. This is opposite to the characteristicsrequired for the thin film transistor (TFT) that needs to have highercarrier density. That is, it can be said that a material having a highercovalent bonding property is suitable for the inorganic semiconductormaterial layer but is not suitable for the thin film transistor.

In the following, an overall description is given of the imaging elementof the present disclosure, the stacked imaging element of the presentdisclosure, and the solid-state imaging device according to the secondaspect of the present disclosure, and thereafter, a detailed descriptionis given of the imaging element and the solid-state imaging device ofExample 1. Symbols representing potentials to be applied to variouselectrodes described below are listed in the following Table 2.

TABLE 2 Charge Charge accumulation transfer period period Firstelectrode V₁₁ V₁₂ Second electrode V₂₁ V₂₂ Charge accumulation electrodeV₃₁ V₃₂ Charge movement control V₄₁ V₄₂ electrode Transfer controlelectrode V₅₁ V₅₂ Charge drain electrode V₆₁ V₆₂

For the sake of convenience, the imaging element or the like of thepresent disclosure that includes the preferred mode described above andthat includes the charge accumulation electrode is hereinafter referredto as an “imaging element or the like including the charge accumulationelectrode of the present disclosure” in some cases.

In the imaging element or the like of the present disclosure, it ispreferred that the inorganic semiconductor material layer have a lighttransmittance of 65% or more for light having a wavelength of 400 nm to660 nm. In addition, it is preferred that the charge accumulationelectrode also have a light transmittance of 65% or more for lighthaving a wavelength of 400 nm to 660 nm. It is preferred that the chargeaccumulation electrode have a sheet resistance of 3×10Ω/□ to 1×10³Ω/□.

In the imaging element or the like of the present disclosure, a mode maybe adopted in which the imaging element or the like further includes asemiconductor substrate, and the photoelectric conversion section isdisposed above the semiconductor substrate. It is to be noted that thefirst electrode, the charge accumulation electrode, the secondelectrode, and the various electrodes are coupled to a drive circuitdescribed later.

The second electrode positioned on light incident side may be shared bya plurality of imaging elements. That is, the second electrode may be aso-called solid electrode except for the imaging elements or the likeincluding an upper charge movement control electrode of the presentdisclosure described later. The photoelectric conversion layer may beshared by a plurality of imaging elements, i.e., one photoelectricconversion layer may be formed for a plurality of imaging elements.Alternatively, the photoelectric conversion layer may be provided foreach imaging element. The inorganic semiconductor material layer ispreferably provided for each imaging element; however, in some cases,may be shared by a plurality of imaging elements. In other words, oneinorganic semiconductor material layer may be formed for a plurality ofimaging elements by providing, for example, a charge movement controlelectrode described later between an imaging element and an imagingelement. In the case where one inorganic semiconductor material layer isformed that is shared by a plurality of imaging elements, it isdesirable that an end part of the inorganic semiconductor material layerbe covered with at least the photoelectric conversion layer from theviewpoint of protection of the end part of the inorganic semiconductormaterial layer.

Further, in the imaging element or the like of the present disclosureincluding the various preferred modes described above, a mode may beadopted in which the first electrode extends in an opening provided inthe insulating layer and is coupled to the inorganic semiconductormaterial layer. Alternatively, a mode may be adopted in which theinorganic semiconductor material layer extends in the opening providedin the insulating layer and is coupled to the first electrode. In thiscase, a mode may be adopted in which:

an edge of a top surface of the first electrode is covered with theinsulating layer,

the first electrode is exposed at a bottom surface of the opening, and

a side surface of the opening is sloped to widen the opening from afirst surface toward a second surface, where the first surface is asurface of the insulating layer in contact with the top surface of thefirst electrode, and the second surface is a surface of the insulatinglayer in contact with a portion of the inorganic semiconductor materiallayer opposed to the charge accumulation electrode, and further the sidesurface of the opening that is sloped to widen the opening from thefirst surface toward the second surface is positioned on side of thecharge accumulation electrode.

Further, in the imaging element or the like including the variouspreferred modes described above, a configuration may be adopted inwhich:

the imaging element or the like further includes a control sectionprovided in the semiconductor substrate and including a drive circuit,

the first electrode and the charge accumulation electrode are coupled tothe drive circuit,

during a charge accumulation period, from the drive circuit, a potentialV₁₁ is applied to the first electrode, a potential V₃₁ is applied to thecharge accumulation electrode, and electric charge is accumulated in theinorganic semiconductor material layer or the like, and

during a charge transfer period, from the drive circuit, a potential V₁₂is applied to the first electrode, a potential V₃₂ is applied to thecharge accumulation electrode, and the electric charge accumulated inthe inorganic semiconductor material layer or the like is read out tothe control section via the first electrode. Note that the potential ofthe first electrode is higher than the potential of the secondelectrode, and

V₃₁ ≥ V₁₁  and  V₃₂ < V₁₂

hold true.

Further, in the imaging element or the like including the variouspreferred modes described above, a mode may be adopted in which thecharge movement control electrode is formed in a region opposed to, withthe insulating layer interposed therebetween, a region of thephotoelectric conversion layer positioned between adjacent imagingelements. It is to be noted that such a mode is referred to as an“imaging element or the like including a lower charge movement controlelectrode of the present disclosure” for the sake of convenience in somecases. Alternatively, a mode may be adopted in which the charge movementcontrol electrode is formed, instead of the second electrode, on theregion of the photoelectric conversion layer positioned between adjacentimaging elements. It is to be noted that such a mode is referred to asan “imaging element or the like including an upper charge movementcontrol electrode of the present disclosure” for the sake of conveniencein some cases.

In the following description, the “region of the photoelectricconversion layer positioned between adjacent imaging elements” isreferred to as a “region-A of the photoelectric conversion layer” forthe sake of convenience, and a “region of the insulating layerpositioned between adjacent imaging elements” is referred to as a“region-A of the insulating layer” for the sake of convenience. Theregion-A of the photoelectric conversion layer corresponds to theregion-A of the insulating layer. Further, a “region between adjacentimaging elements” is referred to as a “region-a” for the sake ofconvenience.

In the imaging element or the like including the lower charge movementcontrol electrode (lower side/charge movement control electrode, acharge movement control electrode positioned on side opposite to thelight incident side with respect to the photoelectric conversion layer)of the present disclosure, the lower charge movement control electrodeis formed in a region opposed to the region-A of the photoelectricconversion layer with the insulating layer interposed therebetween. Inother words, the lower charge movement control electrode is formed belowa portion of the insulating layer (region-A of the insulating layer) ina region (region-a) sandwiched between a charge accumulation electrodeand a charge accumulation electrode that are included in respectiveadjacent imaging elements. The lower charge movement control electrodeis provided at a distance from the charge accumulation electrode. Or inother words, the lower charge movement control electrode surrounds thecharge accumulation electrode and is provided at a distance from thecharge accumulation electrode. The lower charge movement controlelectrode is disposed to be opposed to the region-A of the photoelectricconversion layer with the insulating layer interposed therebetween.

Then, a mode may be adopted in which:

the imaging element or the like including the lower charge movementcontrol electrode of the present disclosure further includes a controlsection provided in the semiconductor substrate and including a drivecircuit,

the first electrode, the second electrode, the charge accumulationelectrode, and the lower charge movement control electrode are coupledto the drive circuit,

during a charge accumulation period, from the drive circuit, a potentialV₁₁ is applied to the first electrode, a potential V₃₁ is applied to thecharge accumulation electrode, a potential V₄₁ is applied to the lowercharge movement control electrode, and electric charge is accumulated inthe inorganic semiconductor material layer or the like, and

during a charge transfer period, from the drive circuit, a potential V₁₂is applied to the first electrode, a potential V₃₂ is applied to thecharge accumulation electrode, a potential V₄₂ is applied to the lowercharge movement control electrode, and the electric charge accumulatedin the inorganic semiconductor material layer or the like is read out tothe control section via the first electrode. Note that:

V₃₁ ≥ V₁₁, V₃₁ > V₄₁  and  V₁₂ > V₃₂ > V₄₂

hold true. The lower charge movement control electrode may be formed ata level the same as or different from that of the first electrode or thecharge accumulation electrode.

In the imaging element or the like including the upper charge movementcontrol electrode (upper side/charge movement control electrode, acharge movement control electrode positioned on the light incident sidewith respect to the photoelectric conversion layer) of the presentdisclosure, the upper charge movement control electrode is formed on theregion of the photoelectric conversion layer positioned between adjacentimaging elements, instead of the second electrode. The upper chargemovement control electrode is provided at a distance from the secondelectrode. In other words:

[A] a mode may be adopted in which: the second electrode is provided foreach imaging element; and the upper charge movement control electrodesurrounds at least a portion of the second electrode and is provided, ata distance from the second electrode, on the region-A of thephotoelectric conversion layer. Alternatively,[B] a mode may be adopted in which: the second electrode is provided foreach imaging element; the upper charge movement control electrodesurrounds at least a portion of the second electrode and is provided ata distance from the second electrode; and a portion of the chargeaccumulation electrode is present below the upper charge movementcontrol electrode. Alternatively,[C] a mode may be adopted in which: the second electrode is provided foreach imaging element; the upper charge movement control electrodesurrounds at least a portion of the second electrode and is provided ata distance from the second electrode; a portion of the chargeaccumulation electrode is present below the upper charge movementcontrol electrode; and furthermore, the lower charge movement controlelectrode is formed below the upper charge movement control electrode.In some cases, a potential generated by coupling between the uppercharge movement control electrode and the second electrode may beapplied to a region of the photoelectric conversion layer positionedbelow a region between the upper charge movement control electrode andthe second electrode.

In addition, a mode may be adopted in which:

the imaging element or the like including the upper charge movementcontrol electrode of the present disclosure further includes a controlsection provided in the semiconductor substrate and including a drivecircuit,

the first electrode, the second electrode, the charge accumulationelectrode, and the upper charge movement control electrode are coupledto the drive circuit,

during a charge accumulation period, from the drive circuit, a potentialV₂₁ is applied to the second electrode, a potential V₄₁ is applied tothe upper charge movement control electrode, and electric charge isaccumulated in the inorganic semiconductor material layer or the like,and

during a charge transfer period, from the drive circuit, a potential V₂₂is applied to the second electrode, a potential V₄₂ is applied to theupper charge movement control electrode, and the electric chargeaccumulated in the inorganic semiconductor material layer or the like isread out to the control section via the first electrode. Note that:

V₂₁ ≥ V₄₁  and  V₂₂ ≥ V₄₂

hold true. The upper charge movement control electrode is formed at alevel the same as that of the second electrode.

Further, in the imaging element or the like of the present disclosureincluding the various preferred modes described above, a mode may beadopted in which the imaging element or the like further includes,between the first electrode and the charge accumulation electrode, atransfer control electrode (charge transfer electrode) disposed at adistance from the first electrode and the charge accumulation electrodeand disposed to be opposed to the inorganic semiconductor material layerwith the insulating layer interposed therebetween. The imaging elementor the like of the present disclosure in such a mode is referred to asan “imaging element or the like including the transfer control electrodeof the present disclosure” for the sake of convenience.

Then, in the imaging element or the like including the transfer controlelectrode of the present disclosure, a mode may be adopted in which:

the imaging element or the like further includes a control sectionprovided in the semiconductor substrate and including a drive circuit,

the first electrode, the charge accumulation electrode, and the transfercontrol electrode are coupled to the drive circuit,

during a charge accumulation period, from the drive circuit, a potentialV₁₁ is applied to the first electrode, a potential V₃₁ is applied to thecharge accumulation electrode, a potential V₅₁ is applied to thetransfer control electrode, and electric charge is accumulated in theinorganic semiconductor material layer or the like, and

during a charge transfer period, from the drive circuit, a potential V₁₂is applied to the first electrode, a potential V₃₂ is applied to thecharge accumulation electrode, a potential V₅₂ is applied to thetransfer control electrode, and the electric charge accumulated in theinorganic semiconductor material layer or the like is read out to thecontrol section via the first electrode. Note that the potential of thefirst electrode is higher than the potential of the second electrode,and

V₃₁ > V₅₁  and  V₃₂ ≤ V₅₂ ≤ V₁₂

hold true.

Further, in the imaging element or the like including the variouspreferred modes described above, a mode may be adopted in which theimaging element or the like further includes a charge drain electrodecoupled to the inorganic semiconductor material layer and disposed at adistance from the first electrode and the charge accumulation electrode.The imaging element or the like of the present disclosure in such a modeis referred to as an “imaging element or the like including the chargedrain electrode of the present disclosure” for the sake of convenience.Then, in the imaging element or the like including the charge drainelectrode of the present disclosure, a mode may be adopted in which thecharge drain electrode is disposed to surround the first electrode andthe charge accumulation electrode (i.e., in a picture frame form). Thecharge drain electrode may be shared by (common to) a plurality ofimaging elements. Then, in this case, a mode may be adopted in which:

the inorganic semiconductor material layer extends in a second openingprovided in the insulating layer and is coupled to the charge drainelectrode,

an edge of a top surface of the charge drain electrode is covered withthe insulating layer,

the charge drain electrode is exposed at a bottom surface of the secondopening, and

a side surface of the second opening is sloped to widen the secondopening from a third surface toward a second surface, where the thirdsurface is a surface of the insulating layer in contact with the topsurface of the charge drain electrode, and the second surface is asurface of the insulating layer in contact with a portion of theinorganic semiconductor material layer opposed to the chargeaccumulation electrode.

Further, in the imaging element or the like including the charge drainelectrode of the present disclosure, a mode may be adopted in which:

the imaging element or the like further includes a control sectionprovided in the semiconductor substrate and including a drive circuit,

the first electrode, the charge accumulation electrode, and the chargedrain electrode are coupled to the drive circuit,

during a charge accumulation period, from the drive circuit, a potentialV₁₁ is applied to the first electrode, a potential V₃₁ is applied to thecharge accumulation electrode, a potential V₆₁ is applied to the chargedrain electrode, and electric charge is accumulated in the inorganicsemiconductor material layer or the like, and

during a charge transfer period, from the drive circuit, a potential V₁₂is applied to the first electrode, a potential V₃₂ is applied to thecharge accumulation electrode, a potential V₆₂ is applied to the chargedrain electrode, and the electric charge accumulated in the inorganicsemiconductor material layer or the like is read out to the controlsection via the first electrode. Note that the potential of the firstelectrode is higher than the potential of the second electrode, and

V₆₁ > V₁₁  and  V₆₂ < V₁₂

hold true.

Further, in the above-described various preferred modes of the imagingelement or the like of the present disclosure, a mode may be adopted inwhich the charge accumulation electrode includes a plurality of chargeaccumulation electrode segments. The imaging element or the like of thepresent disclosure in such a mode is referred to as an “imaging elementor the like including a plurality of charge accumulation electrodesegments of the present disclosure” for the sake of convenience. It issufficient that the number of the charge accumulation electrode segmentsis two or more. In the imaging element or the like including a pluralityof charge accumulation electrode segments of the present disclosure, ina case where different potentials are applied to N charge accumulationelectrode segments, a mode may be adopted in which:

in a case where the potential of the first electrode is higher than thepotential of the second electrode, during the charge transfer period,the potential to be applied to a charge accumulation electrode segment(a first photoelectric conversion section segment) positioned closest tothe first electrode is higher than the potential to be applied to acharge accumulation electrode segment (an N-th photoelectric conversionsection segment) positioned farthest from the first electrode, and

in a case where the potential of the first electrode is lower than thepotential of the second electrode, during the charge transfer period,the potential to be applied to the charge accumulation electrode segment(the first photoelectric conversion section segment) positioned closestto the first electrode is lower than the potential to be applied to thecharge accumulation electrode segment (the N-th photoelectric conversionsection segment) positioned farthest from the first electrode.

In the imaging element or the like of the present disclosure includingthe various preferred modes described above, a configuration may beadopted in which:

at least a floating diffusion layer and an amplification transistorincluded in the control section are provided in the semiconductorsubstrate, and

the first electrode is coupled to the floating diffusion layer and agate section of the amplification transistor. Then, in this case,furthermore, a configuration may be adopted in which:

a reset transistor and a selection transistor included in the controlsection are further provided in the semiconductor substrate,

the floating diffusion layer is coupled to one of source/drain regionsof the reset transistor, and

one of source/drain regions of the amplification transistor is coupledto one of source/drain regions of the selection transistor, and anotherone of the source/drain regions of the selection transistor is coupledto a signal line.

Further, in the imaging element or the like of the present disclosureincluding the various preferred modes described above, a mode may beadopted in which the charge accumulation electrode is larger in sizethan the first electrode. Although not limited,

4 ≤ s₁^(′)/s₁

is preferably satisfied, where s₁′ denotes the area of the chargeaccumulation electrode, and s₁ denotes the area of the first electrode.

Alternatively, as modification examples of the imaging element or thelike of the present disclosure including the various preferred modesdescribed above, imaging elements of first to sixth configurationsdescribed below may be adopted. That is, in the imaging elements of thefirst to sixth configurations in the imaging element or the like of thepresent disclosure including the various preferred modes describedabove,

the photoelectric conversion section includes N (where N≥2)photoelectric conversion section segments,

the inorganic semiconductor material layer and the photoelectricconversion layer include N photoelectric conversion layer segments,

the insulating layer includes N insulating layer segments,

in the imaging elements of the first to third configurations, the chargeaccumulation electrode includes N charge accumulation electrodesegments,

in the imaging elements of the fourth and fifth configurations, thecharge accumulation electrode includes N charge accumulation electrodesegments disposed at a distance from each other,

an n-th (where n=1, 2, 3 . . . N) photoelectric conversion sectionsegment includes an n-th charge accumulation electrode segment, an n-thinsulating layer segment, and an n-th photoelectric conversion layersegment, and

the photoelectric conversion section segment with a larger value of n ispositioned farther away from the first electrode. Here, the“photoelectric conversion layer segment” refers to a segment includingthe photoelectric conversion layer and the inorganic semiconductormaterial layer that are stacked.

Then, in the imaging element of the first configuration, the thicknessesof the insulating layer segments gradually change from the firstphotoelectric conversion section segment to the N-th photoelectricconversion section segment. In addition, in the imaging element of thesecond configuration, the thicknesses of the photoelectric conversionlayer segments gradually change from the first photoelectric conversionsection segment to the N-th photoelectric conversion section segment. Itis to be noted that, in the photoelectric conversion layer segment, thethickness of the photoelectric conversion layer segment may be changedby changing the thickness of the portion of the photoelectric conversionlayer while making the thickness of the portion of the inorganicsemiconductor material layer constant. The thickness of thephotoelectric conversion layer segment may be changed by changing thethickness of the portion of the inorganic semiconductor material layerwhile making the thickness of the portion of the photoelectricconversion layer constant. The thickness of the photoelectric conversionlayer segment may be changed by changing the thickness of the portion ofthe photoelectric conversion layer and changing the thickness of theportion of the inorganic semiconductor material layer. Further, in theimaging element of the third configuration, materials included in theinsulating layer segments are different between adjacent photoelectricconversion section segments. In addition, in the imaging element of thefourth configuration, materials included in the charge accumulationelectrode segments are different between adjacent photoelectricconversion section segments. Further, in the imaging element of thefifth configuration, the areas of the charge accumulation electrodesegments gradually decrease from the first photoelectric conversionsection segment to the N-th photoelectric conversion section segment.The areas may decrease continuously or may decrease stepwise.

Alternatively, in the imaging element of the sixth configuration in theimaging element or the like of the present disclosure including thevarious preferred modes described above, the cross-sectional area of astacked portion in which the charge accumulation electrode, theinsulating layer, the inorganic semiconductor material layer, and thephotoelectric conversion layer are stacked, as cut along a Y-Z virtualplane, changes in accordance with a distance from the first electrode,where a Z direction is a stacking direction of the charge accumulationelectrode, the insulating layer, the inorganic semiconductor materiallayer, and the photoelectric conversion layer, and an X direction is adirection away from the first electrode. The change in thecross-sectional area may be a continuous change or may be a stepwisechange.

In the imaging elements of the first and second configurations, the Nphotoelectric conversion layer segments are continuously provided, the Ninsulating layer segments are also continuously provided, and the Ncharge accumulation electrode segments are also continuously provided.In the imaging elements of the third to fifth configurations, the Nphotoelectric conversion layer segments are continuously provided. Inaddition, in the imaging elements of the fourth and fifthconfigurations, the N insulating layer segments are continuouslyprovided, whereas in the imaging element of the third configuration, theN insulating layer segments are provided to correspond to the respectivephotoelectric conversion section segments. Further, in the imagingelements of the fourth and fifth configurations, and in the imagingelement of the third configuration depending on the case, the N chargeaccumulation electrode segments are provided to correspond to therespective photoelectric conversion section segments. Then, in theimaging elements of the first to sixth configurations, the samepotential is applied to all of the charge accumulation electrodesegments. Alternatively, in the imaging elements of the fourth and fifthconfigurations, and in the imaging element of the third configurationdepending on the case, different potentials may be applied to the Ncharge accumulation electrode segments.

In the imaging element or the like of the present disclosure includingany of the imaging elements of the first to sixth configurations, thethicknesses of the insulating layer segments are defined. Alternatively,the thicknesses of the photoelectric conversion layer segments aredefined. Alternatively, the materials included in the insulating layersegments are different. Alternatively, the materials included in thecharge accumulation electrode segments are different. Alternatively, theareas of the charge accumulation electrode segments are defined.Alternatively, the cross-sectional area of the stacked portion isdefined. Therefore, a kind of charge transfer gradient is formed, and itbecomes possible to transfer the electric charge generated by thephotoelectric conversion to the first electrode more easily and withreliability. Then, as a result, it is possible to prevent generation ofresidual image or prevent some electric charge from remaininguntransferred.

In the imaging elements of the first to fifth configurations, thephotoelectric conversion section segment with a larger value of n ispositioned farther away from the first electrode. Whether or not thephotoelectric conversion section segment is positioned away from thefirst electrode is determined with respect to the X direction. Inaddition, while the direction away from the first electrode is the Xdirection in the imaging element of the sixth configuration, the “Xdirection” is defined as follows. That is, a pixel region in which aplurality of imaging elements or stacked imaging elements are arrangedincludes a plurality of pixels arranged in a two-dimensional array,i.e., arranged systematically in the X direction and the Y direction. Ina case where the plane shape of the pixels is rectangular, the directionin which the side closest to the first electrode extends is the Ydirection, and the direction orthogonal to the Y direction is the Xdirection. Alternatively, in a case where the pixels have any planeshape, an overall direction including the line segment or curve closestto the first electrode is the Y direction, and the direction orthogonalto the Y direction is the X direction.

In relation to the imaging elements of the first to sixthconfigurations, description is given below of a case where the potentialof the first electrode is higher than the potential of the secondelectrode.

In the imaging element of the first configuration, the thicknesses ofthe insulating layer segments gradually change from the firstphotoelectric conversion section segment to the N-th photoelectricconversion section segment. It is preferred that the thicknesses of theinsulating layer segments gradually increase. This forms a kind ofcharge transfer gradient. Then, when a state of V₃₁≥V₁₁ is establishedin the charge accumulation period, the n-th photoelectric conversionsection segment is able to accumulate more electric charge and issubjected to a more intense electric field than the (n+1)-thphotoelectric conversion section segment. This makes it possible toprevent the flow of electric charge from the first photoelectricconversion section segment to the first electrode with reliability. Inaddition, when a state of V₃₂<V₁₂ is established in the charge transferperiod, it is possible to secure the flow of electric charge from thefirst photoelectric conversion section segment to the first electrodeand the flow of electric charge from the (n+1)-th photoelectricconversion section segment to the n-th photoelectric conversion sectionsegment with reliability.

In the imaging element of the second configuration, the thicknesses ofthe photoelectric conversion layer segments gradually change from thefirst photoelectric conversion section segment to the N-th photoelectricconversion section segment. It is preferred that the thicknesses of thephotoelectric conversion layer segments gradually increase. This forms akind of charge transfer gradient. Then, when a state of V₃₁≥V₁₁ isestablished in the charge accumulation period, a more intense electricfield is applied to the n-th photoelectric conversion section segmentthan to the (n+1)-th photoelectric conversion section segment. Thismakes it possible to prevent the flow of electric charge from the firstphotoelectric conversion section segment to the first electrode withreliability. In addition, when a state of V₃₂<V₁₂ is established in thecharge transfer period, it is possible to secure the flow of electriccharge from the first photoelectric conversion section segment to thefirst electrode and the flow of electric charge from the (n+1)-thphotoelectric conversion section segment to the n-th photoelectricconversion section segment with reliability.

In the imaging element of the third configuration, the materialsincluded in the insulating layer segments are different between adjacentphotoelectric conversion section segments, and this forms a kind ofcharge transfer gradient. It is preferred that the values of dielectricconstant of the materials included in the insulating layer segmentsgradually decrease from the first photoelectric conversion sectionsegment to the N-th photoelectric conversion section segment. With sucha configuration employed, when a state of V₃₁≥V₁₁ is established in thecharge accumulation period, the n-th photoelectric conversion sectionsegment is able to accumulate more electric charge than the (n+1)-thphotoelectric conversion section segment. In addition, when a state ofV₃₂<V₁₂ is established in the charge transfer period, it is possible tosecure the flow of electric charge from the first photoelectricconversion section segment to the first electrode and the flow ofelectric charge from the (n+1)-th photoelectric conversion sectionsegment to the n-th photoelectric conversion section segment withreliability.

In the imaging element of the fourth configuration, the materialsincluded in the charge accumulation electrode segments are differentbetween adjacent photoelectric conversion section segments, and thisforms a kind of charge transfer gradient. It is preferred that thevalues of work function of the materials included in the insulatinglayer segments gradually increase from the first photoelectricconversion section segment to the N-th photoelectric conversion sectionsegment. With such a configuration employed, it is possible to form apotential gradient advantageous for signal charge transfer regardless ofwhether the voltage (potential) is positive or negative.

In the imaging element of the fifth configuration, the areas of thecharge accumulation electrode segments gradually decrease from the firstphotoelectric conversion section segment to the N-th photoelectricconversion section segment, and this forms a kind of charge transfergradient. Therefore, when the state of V₃₁≥V₁₁ is established in thecharge accumulation period, the n-th photoelectric conversion sectionsegment is able to accumulate more electric charge than the (n+1)-thphotoelectric conversion section segment. In addition, when a state ofV₃₂<V₁₂ is established in the charge transfer period, it is possible tosecure the flow of electric charge from the first photoelectricconversion section segment to the first electrode and the flow ofelectric charge from the (n+1)-th photoelectric conversion sectionsegment to the n-th photoelectric conversion section segment withreliability.

In the imaging element of the sixth configuration, the cross-sectionalarea of the stacked portion changes in accordance with the distance fromthe first electrode, and this forms a kind of charge transfer gradient.Specifically, by employing a configuration in which the thickness of thecross section of the stacked portion is constant and the width of thecross section of the stacked portion decreases as being away from thefirst electrode, it becomes possible for a region near the firstelectrode to accumulate more electric charge than a region far from thefirst electrode when the state of V₃₁≥V₁₁ is established in the chargeaccumulation period, similarly to the description of the imaging elementof the fifth configuration. Therefore, when the state of V₃₂<V₁₂ isestablished in the charge transfer period, it is possible to secure theflow of electric charge from the region near the first electrode to thefirst electrode and the flow of electric charge from the far region tothe near region with reliability. In contrast, by employing aconfiguration in which the width of the cross section of the stackedportion is constant and the thickness of the cross section of thestacked portion, specifically, the thickness of the insulating layersegment is gradually increased, when the state of V₃₁≥V₁₁ is establishedin the charge accumulation period, the region near the first electrodeis able to accumulate more electric charge and is subjected to a moreintense electric field than the region far from the first electrode,making it possible to prevent the flow of electric charge from theregion near the first electrode to the first electrode with reliability,similarly to the description of the imaging element of the firstconfiguration. Then, when the state of V₃₂<V₁₂ is established in thecharge transfer period, it is possible to secure the flow of electriccharge from the region near the first electrode to the first electrodeand the flow of electric charge from the far region to the near regionwith reliability. In addition, by employing the configuration in whichthe thicknesses of the photoelectric conversion layer segments aregradually increased, a more intense electric field is applied to theregion near the first electrode than to the region far from the firstelectrode when the state of V₃₁≥V₁₁ is established in the chargeaccumulation period, making it possible to prevent the flow of electriccharge from the region near the first electrode to the first electrodewith reliability, similarly to the description of the imaging element ofthe second configuration. Then, when the state of V₃₂<V₁₂ is establishedin the charge transfer period, it is possible to secure the flow ofelectric charge from the region near the first electrode to the firstelectrode and the flow of electric charge from the far region to thenear region with reliability.

Two or more of the imaging elements of the first to sixth configurationsincluding the preferred modes described above may be appropriatelycombined as desired.

As a modification example of the solid-state imaging devices accordingto the first and second aspects of the present disclosure, a solid-stateimaging device may have a configuration in which

the solid-state imaging device includes any of a plurality of theimaging elements of the first to sixth configurations,

the plurality of imaging elements constitute an imaging element block,and

the first electrode is shared by the plurality of imaging elementsconstituting the imaging element block. The solid-state imaging devicehaving such a configuration is referred to as a “solid-state imagingdevice of a first configuration” for the sake of convenience.Alternatively, as a modification example of the solid-state imagingdevices according to the first and second aspects of the presentdisclosure, a solid-state imaging device may have a configuration inwhich

the solid-state imaging device includes any of a plurality of theimaging elements of the first to sixth configurations or a plurality ofstacked imaging elements including at least one of the imaging elementsof the first to sixth configurations,

the plurality of imaging elements or stacked imaging elementsconstitutes an imaging element block, and

the first electrode is shared by the plurality of imaging elements orstacked imaging elements constituting the imaging element block. Thesolid-state imaging device having such a configuration is referred to asa “solid-state imaging device of a second configuration” for the sake ofconvenience. Then, by allowing the first electrode to be shared by theplurality of imaging elements constituting the imaging element block asdescribed above, it is possible to simplify and miniaturize theconfiguration and structure of the pixel region in which a plurality ofimaging elements are arranged.

In the solid-state imaging devices of the first and secondconfigurations, one floating diffusion layer is provided for a pluralityof imaging elements (one imaging element block). Here, the plurality ofimaging elements provided for one floating diffusion layer may include aplurality of imaging elements of a first type described later, or mayinclude at least one imaging element of the first type and one or two ormore imaging elements of a second type described later. Then,appropriately controlling the timing of the charge transfer periodallows for sharing of one floating diffusion layer among the pluralityof imaging elements. The plurality of imaging elements is caused tooperate together and is coupled as an imaging element block to a drivecircuit described later. That is, the plurality of imaging elementsconstituting the imaging element block is coupled to one drive circuit.However, control of the charge accumulation electrode is performed foreach imaging element. In addition, it is possible for the plurality ofimaging elements to share one contact hole section. The arrangementrelationship between the first electrode shared by the plurality ofimaging elements and the charge accumulation electrode of each imagingelement may be such that, in some cases, the first electrode is disposedto be adjacent to the charge accumulation electrode of each imagingelement. Alternatively, the first electrode may be disposed to beadjacent to the charge accumulation electrodes of some of the pluralityof imaging elements and not disposed to be adjacent to the chargeaccumulation electrodes of the rest of the plurality of imagingelements. In this case, the movement of electric charge from the rest ofthe plurality of imaging elements to the first electrode is movement viasome of the plurality of imaging elements. In order to ensure movementof electric charge from each imaging element to the first electrode, itis preferred that a distance between a charge accumulation electrodeincluded in an imaging element and a charge accumulation electrodeincluded in an imaging element (referred to as a “distance A” for thesake of convenience) be longer than a distance between the firstelectrode and the charge accumulation electrode in an imaging elementadjacent to the first electrode (referred to as a “distance B” for thesake of convenience). In addition, it is preferred that the value of thedistance Abe larger in the imaging element positioned farther away fromthe first electrode. It is to be noted that the description above isapplicable not only to the solid-state imaging devices of the first andsecond configurations but also to the solid-state imaging devices of thefirst and second aspects of the present disclosure.

Further, in the imaging element or the like of the present disclosureincluding the various preferred modes described above, a mode may beadopted in which light enters from side of the second electrode, and alight-blocking layer is formed on the light incident side closer to thesecond electrode. Alternatively, a mode may be adopted in which lightenters from the side of the second electrode, and no light enters thefirst electrode (depending on the case, light enters neither of thefirst electrode and the transfer control electrode). Then, in this case,a configuration may be adopted in which the light-blocking layer isformed on the light incident side closer to the second electrode andabove the first electrode (depending on the case, the first electrodeand the transfer control electrode). Alternatively, a configuration maybe adopted in which an on-chip microlens is provided above the chargeaccumulation electrode and the second electrode, and the light enteringthe on-chip microlens is condensed onto the charge accumulationelectrode. Here, the light-blocking layer may be disposed above thesurface of the second electrode on the light incident side, or may bedisposed on the surface of the second electrode on the light incidentside. The light-blocking layer may be formed in the second electrodedepending on the case. Examples of a material to be included inlight-blocking layer include chromium (Cr), copper (Cu), aluminum (Al),tungsten (W), and non-light-transmitting resins (e.g., polyimide resin).

Specific examples of the imaging element or the like of the presentdisclosure include: an imaging element (referred to as a “blue lightimaging element of a first type” for the sake of convenience) that hassensitivity to blue light and includes a photoelectric conversion layeror a photoelectric conversion section (referred to as a “blue lightphotoelectric conversion layer of a first type” or a “blue lightphotoelectric conversion section of a first type” for the sake ofconvenience) that absorbs blue light (light at 425 nm to 495 nm); animaging element (referred to as a “green light imaging element of afirst type” for the sake of convenience) that has sensitivity to greenlight and includes a photoelectric conversion layer or a photoelectricconversion section (referred to as a “green light photoelectricconversion layer of a first type” or a “green light photoelectricconversion section of a first type” for the sake of convenience) thatabsorbs green light (light at 495 nm to 570 nm); and an imaging element(referred to as a “red light imaging element of a first type” for thesake convenience) that has sensitivity to red light and includes aphotoelectric conversion layer or a photoelectric conversion section(referred to as a “red light photoelectric conversion layer of a firsttype” or a “red light photoelectric conversion section of a first type”for the sake of convenience) that absorbs red light (light at 620 nm to750 nm). In addition, an existing imaging element that does not includethe charge accumulation electrode and that has sensitivity to blue lightis referred to as a “blue light imaging element of a second type” forthe sake convenience. An existing imaging element that does not includethe charge accumulation electrode and that has sensitivity to greenlight is referred to as a “green light imaging element of a second type”for the sake of convenience. An existing imaging element that does notinclude the charge accumulation electrode and that has sensitivity tored light is referred to as a “red light imaging element of a secondtype” for the sake of convenience. A photoelectric conversion layer or aphotoelectric conversion section included in the blue light imagingelement of the second type is referred to as a “blue light photoelectricconversion layer of a second type” or a “blue light photoelectricconversion section of a second type” for the sake of convenience. Aphotoelectric conversion layer or a photoelectric conversion sectionincluded in the green light imaging element of the second type isreferred to as a “green light photoelectric conversion layer of a secondtype” or a “green light photoelectric conversion section of a secondtype” for the sake of convenience. A photoelectric conversion layer or aphotoelectric conversion section included in the red light imagingelement of the second type is referred to as a “red light photoelectricconversion layer of a second type” or a “red light photoelectricconversion section of a second type” for the sake of convenience.

The stacked imaging element of the present disclosure includes at leastone imaging element or the like (photoelectric conversion element) ofthe present disclosure, and specific examples of the configuration andstructure of the stacked imaging element include:

[A] a configuration and a structure in which the blue lightphotoelectric conversion section of the first type, the green lightphotoelectric conversion section of the first type, and the red lightphotoelectric conversion section of the first type are stacked in avertical direction, and the control sections of the blue light imagingelement of the first type, the green light imaging element of the firsttype, and the red light imaging element of the first type are eachprovided in the semiconductor substrate;[B] a configuration and a structure in which the blue lightphotoelectric conversion section of the first type and the green lightphotoelectric conversion section of the first type are stacked in thevertical direction,

the red light photoelectric conversion section of the second type isdisposed below these two layers of photoelectric conversion sections ofthe first type, and

the control sections of the blue light imaging element of the firsttype, the green light imaging element of the first type, and the redlight imaging element of the second type are each provided in thesemiconductor substrate;

[C] a configuration and a structure in which the blue lightphotoelectric conversion section of the second type and the red lightphotoelectric conversion section of the second type are disposed belowthe green light photoelectric conversion section of the first type, and

the control sections of the green light imaging element of the firsttype, the blue light imaging element of the second type, and the redlight imaging element of the second type are each provided in thesemiconductor substrate; and

[D] a configuration and a structure in which the green lightphotoelectric conversion section of the second type and the red lightphotoelectric conversion section of the second type are disposed belowthe blue light photoelectric conversion section of the first type, and

the control sections of the blue light imaging element of the firsttype, the green light imaging element of the second type, and the redlight imaging element of the second type are each provided in thesemiconductor substrate. It is preferred that the arrangement order ofthe photoelectric conversion sections of these imaging elements in thevertical direction be the order of the blue light photoelectricconversion section, the green light photoelectric conversion section,and the red light photoelectric conversion section from light incidentdirection, or the order of the green light photoelectric conversionsection, the blue light photoelectric conversion section, and the redlight photoelectric conversion section from the light incidentdirection. One reason for this is that the light of a shorter wavelengthis efficiently absorbed on incident surface side. Red has the longestwavelength among the three colors, and it is therefore preferred thatthe red light photoelectric conversion section be positioned in thelowest layer as viewed from light incident surface. One pixel isconfigured by the stacked structure of these imaging elements. Inaddition, a near-infrared photoelectric conversion section(alternatively, an infrared photoelectric conversion section) of a firsttype may be provided. Here, it is preferred that the photoelectricconversion layer of the infrared photoelectric conversion section of thefirst type include, for example, an organic material and be disposed inthe lowest layer of the stacked structure of the imaging elements of thefirst type and above the imaging elements of the second type.Alternatively, a near-infrared photoelectric conversion section(alternatively, an infrared photoelectric conversion section) of asecond type may be provided below the photoelectric conversion sectionsof the first type.

In the imaging elements of the first type, the first electrode is formedon, for example, an interlayer insulating layer provided on thesemiconductor substrate. The imaging element formed on the semiconductorsubstrate may be of a back illuminated type or a front illuminated type.

In a case where the photoelectric conversion layer includes an organicmaterial, any one of the following four aspects may be adopted for thephotoelectric conversion layer.

(1) The photoelectric conversion layer includes a p-type organicsemiconductor.(2) The photoelectric conversion layer includes an n-type organicsemiconductor.(3) The photoelectric conversion layer includes a stacked structure of ap-type organic semiconductor layer/an n-type organic semiconductorlayer. The photoelectric conversion layer includes a stacked structureof a p-type organic semiconductor layer/a mixed layer (bulk heterostructure) of a p-type organic semiconductor and an n-type organicsemiconductor/an n-type organic semiconductor layer. The photoelectricconversion layer includes a stacked structure of a p-type organicsemiconductor layer/a mixed layer (bulk hetero structure) of a p-typeorganic semiconductor and an n-type organic semiconductor. Thephotoelectric conversion layer includes a stacked structure of an n-typeorganic semiconductor layer/a mixed layer (bulk hetero structure) of ap-type organic semiconductor and an n-type organic semiconductor.(4) The photoelectric conversion layer includes a mixture (bulk heterostructure) of a p-type organic semiconductor and an n-type organicsemiconductor. Note that the order of stacking may be changedarbitrarily.

Examples of the p-type organic semiconductor include a naphthalenederivative, an anthracene derivative, a phenanthrene derivative, apyrene derivative, a perylene derivative, a tetracene derivative, apentacene derivative, a quinacridone derivative, a thiophene derivative,a thienothiophene derivative, a benzothiophene derivative, abenzothienobenzothiophene derivative, a triallylamine derivative, acarbazole derivative, a perylene derivative, a picene derivative, achrysene derivative, a fluoranthene derivative, a phthalocyaninederivative, a subphthalocyanine derivative, a subporphyrazinederivative, a metal complex including heterocyclic compounds as ligands,a polythiophene derivative, a polybenzothiadiazole derivative, and apolyfluorene derivative. Examples of the n-type organic semiconductorinclude a fullerene and a fullerene derivative <for example, fullerene(higher fullerene), such as C60, C70, and C74, endohedral fullerene, orthe like) or fullerene derivative (e.g., fullerene fluoride, PCBMfullerene compound, fullerene multimer, or the like)>, an organicsemiconductor with larger (deeper) HOMO and LUMO than the p-type organicsemiconductor, and transparent inorganic metal oxide. Specific examplesof the n-type organic semiconductor include organic molecules including,as part of molecular framework, a heterocyclic compound containingnitrogen atoms, oxygen atoms, and sulfur atoms, such as a pyridinederivative, a pyrazine derivative, a pyrimidine derivative, a triazinederivative, a quinoline derivative, a quinoxaline derivative, anisoquinoline derivative, an acridine derivative, a phenazine derivative,a phenanthroline derivative, a tetrazole derivative, a pyrazolederivative, an imidazole derivative, a thiazole derivative, an oxazolederivative, an imidazole derivative, a benzimidazole derivative, abenzotriazole derivative, a benzoxazole derivative, a benzoxazolederivative, a carbazole derivative, a benzofuran derivative, adibenzofuran derivative, a subporphyrazine derivative, a polyphenylenevinylene derivative, a polybenzothiadiazole derivative, and apolyfluorene derivative, an organic metal complex, and asubphthalocyanine derivative. Examples of groups and the like includedin the fullerene derivative include: halogen atoms; a straight-chain,branched, or cyclic alkyl group or phenyl group; a group including astraight-chain or condensed aromatic compound; a group including halide;a partial fluoroalkyl group; a perfluoroalkyl group; a silylalkyl group;a silylalkoxy group; an arylsilyl group; an arylsulfanyl group; analkylsulfanyl group; an arylsulfonyl group; an alkylsulfonyl group; anarylsulfide group; an alkylsulfide group; an amino group; an alkylaminogroup; an arylamino group; a hydroxy group; an alkoxy group; anacylamino group; an acyloxy group; a carbonyl group; a carboxy group; acarboxamide group; a carboalkoxy group; an acyl group; a sulfonyl group;a cyano group; a nitro group; a group including chalcogenide; aphosphine group; a phosphon group; and derivatives thereof. Thickness ofthe photoelectric conversion layer including an organic material (whichis referred to as an “organic photoelectric conversion layer” in somecases) is not limited and may be, for example, 1×10⁻⁸ m to 5×10⁻⁷ m,preferably, 2.5×10⁻⁸ m to 3×10⁻⁷ m, more preferably, 2.5×10⁻⁸ m to2×10⁻⁷ m, still more preferably, 1×10⁻⁷ m to 1.8×10⁻⁷ m. It is to benoted that the organic semiconductors are often classified into p-typeand n-type. The p-type means that the holes are easily transportable,and the n-type means that the electrons are easily transportable. Theorganic semiconductor is not limited to the interpretation that it hasholes or electrons as majority carriers of thermal excitation, as ininorganic semiconductors.

Alternatively, examples of a material to be included in the organicphotoelectric conversion layer for performing photoelectric conversionof green light include a rhodamine-based dye, a merocyanine-based dye, aquinacridone derivative, a subphthalocyanine-based dye(subphthalocyanine derivative), and the like. Examples of a material tobe included in the organic photoelectric conversion layer for performingphotoelectric conversion of blue light include a coumaric acid dye,tris-8-hydroxyquinoline aluminum (Alq3), a merocyanine-based dye, andthe like. Examples of a material to be included in the organicphotoelectric conversion layer for performing photoelectric conversionof red light include a phthalocyanine-based dye, asubphthalocyanine-based dye (subphthalocyanine derivative), and thelike.

Alternatively, examples of the inorganic material to be included in thephotoelectric conversion layer include crystalline silicon, amorphoussilicon, microcrystalline silicone, crystalline selenium, amorphousselenium, chalcopyrite compounds, such as CIGS (CuInGaSe), CIS(CuInSe₂), CuInS₂, CuAlS₂, CuAlSe₂, CuGaS₂, CuGaSe₂, AgAlS₂, AgAlSe₂,AgInS₂, and AgInSe₂, or group III-V compounds, such as GaAs, InP,AlGaAs, InGaP, AlGaInP, and InGaAsP, and furthermore, compoundsemiconductors of CdSe, CdS, In₂Se₃, In₂S₃, Bi₂Se₃, Bi₂S₃, ZnSe, ZnS,PbSe, PbS, and the like. In addition, quantum dots including thesematerials are also usable for the photoelectric conversion layer.

The solid-state imaging devices according to the first and secondaspects of the present disclosure and the solid-state imaging devices ofthe first and second configurations are able to configure single-platecolor solid-state imaging devices.

In the solid-state imaging device according to the second aspect of thepresent disclosure including the stacked imaging element, the imagingelements having sensitivity to light of a plurality of types ofwavelengths are stacked in the direction in which light enters withinthe same pixel to constitute one pixel, unlike in a solid-state imagingdevice including imaging elements in Bayer arrangement (i.e., not usinga color filter layer for performing blue, green, or red spectralseparation). It is therefore possible to achieve improvement ofsensitivity and improvement of the pixel density per unit volume. Inaddition, organic materials are high in absorption coefficient, and thusmake it possible to reduce the thickness of the organic photoelectricconversion layer compared with an existing Si-based photoelectricconversion layer. This reduces leakage of light from adjacent pixels andeases restrictions on a light incident angle. Further, while existingSi-based imaging elements suffer from generation of false colors becausean interpolation process is performed for pixels of three colors tocreate color signals, the generation of the false colors is suppressedin the solid-state imaging device according to the second aspect of thepresent disclosure including the stacked imaging element. The organicphotoelectric conversion layer itself also serves as a color filterlayer, and therefore it is possible to separate the colors withoutdisposing a color filter layer.

Meanwhile, in the solid-state imaging device according to the firstaspect of the present disclosure, employing the color filter layer makesit possible to ease requirements on the spectral characteristics ofblue, green, and red, and provides high mass productivity. Examples ofarrangement of the imaging elements in the solid-state imaging deviceaccording to the first aspect of the present disclosure include aninterline arrangement, a G stripe RB checkered arrangement, a G stripeRB full checkered arrangement, a checkered complementary colorarrangement, a stripe arrangement, a diagonal stripe arrangement, aprimary color difference arrangement, a field color differencesequential arrangement, a frame color difference sequential arrangement,a MOS arrangement, an improved MOS arrangement, a frame interleavearrangement, and a field interleave arrangement, as well as the Bayerarrangement. Here, one imaging element constitutes one pixel (orsubpixel).

Examples of the color filter layers (wavelength selection means) includefilter layers that transmit not only red, green, and blue, but alsospecific wavelengths, such as cyan, magenta, and yellow, depending onthe case. It is possible for the color filter layer to be configured notonly by an organic material-based color filter layer using an organiccompound such as a pigment or a dye, but also by a thin film includingan inorganic material such as a photonic crystal, a wavelength selectionelement based on application of plasmon (color filter layer having aconductor lattice structure with a lattice-like hole structure in aconductive thin film; see, for example, Japanese Unexamined PatentApplication Publication No. 2008-177191), or amorphous silicon.

The pixel region in which a plurality of imaging elements or the like ofthe present disclosure or stacked imaging elements of the presentdisclosure are arranged includes a plurality of pixels systematicallyarranged in a two-dimensional array. The pixel region typicallyincludes: an effective pixel region in which light is actually receivedto generate signal charge through photoelectric conversion, and thesignal charge is amplified and read out to the drive circuit; and ablack reference pixel region (also called an optical black pixel region(OPB)) for outputting optical black serving as a black level reference.The black reference pixel region is typically disposed on the outerperiphery of the effective pixel region.

In the imaging element or the like of the present disclosure includingthe various preferred modes described above, irradiation with light isperformed, photoelectric conversion is generated in the photoelectricconversion layer, and holes and electrons are subjected to carrierseparation. Then, an electrode from which the holes are extracted is ananode, and an electrode from which the electrons are extracted is acathode. The first electrode constitutes the cathode, and the secondelectrode constitutes the anode.

A configuration may be adopted in which the first electrode, the chargeaccumulation electrode, the transfer control electrode, the chargemovement control electrode, the charge drain electrode, and the secondelectrode include transparent electrically-conductive materials. Thefirst electrode, the charge accumulation electrode, the transfer controlelectrode, and the charge drain electrode are collectively referred toas a “first electrode or the like” in some cases. Alternatively, in acase where the imaging elements or the like of the present disclosureare arranged on a plane as in, for example, a Bayer arrangement, aconfiguration may be adopted in which the second electrode includes atransparent electrically-conductive material, and the first electrode orthe like includes a metal material. In this case, specifically, aconfiguration may be adopted in which the second electrode positioned onthe light incident side includes a transparent electrically-conductivematerial, and the first electrode or the like includes, for example,Al—Nd (alloy of aluminum and neodymium) or ASC (alloy of aluminum,samarium, and copper). An electrode including a transparentelectrically-conductive material is referred to as a “transparentelectrode” in some cases. Here, it is desirable that the band-gap energyof the transparent electrically-conductive material be 2.5 eV or more,preferably, 3.1 eV or more. Examples of the transparentelectrically-conductive material to be included in the transparentelectrode include electrically-conductive metal oxides. Specifically,examples of the transparent electrically-conductive material includeindium oxide, indium-tin oxide (ITO, Indium Tin Oxide, includingSn-doped In₂O₃, crystalline ITO, and amorphous ITO), indium-zinc oxide(IZO, Indium Zinc Oxide) in which indium is added as a dopant to zincoxide, indium-gallium oxide (IGO) in which indium is added as a dopantto gallium oxide, indium-gallium-zinc oxide (IGZO, In—GaZnO₄) in whichindium and gallium are added as dopants to zinc oxide, indium-tin-zincoxide (ITZO) in which indium and tin are added as dopants to zinc oxide,IFO (F-doped In₂O₃), tin oxide (SnO₂), ATO (Sb-doped SnO₂), FTO (F-dopedSnO₂), zinc oxide (including ZnO doped with another element),aluminum-zinc oxide (AZO) in which aluminum is added as a dopant to zincoxide, gallium-zinc oxide (GZO) in which gallium is added as a dopant tozinc oxide, titanium oxide (TiO₂), niobium-titanium oxide (TNO) in whichniobium is added as a dopant to titanium oxide, antimony oxide, CuI,InSbO₄, ZnMgO, CuInO₂, MgIn₂O₄, CdO, ZnSnO₃, spinel oxide, and an oxidehaving YbFe₂O₄ structure. Alternatively, the transparent electrode mayinclude gallium oxide, titanium oxide, niobium oxide, nickel oxide, orthe like as a mother layer. An example of the thickness of thetransparent electrode may be 2×10⁻⁸ m to 2×10⁻⁷ m, preferably, 3×10⁻⁸ mto 1×10⁻⁷ m. In a case where the first electrode has to be transparent,it is preferred that the charge drain electrode also include atransparent electrically-conductive material, from the viewpoint ofsimplification of the manufacturing process.

Alternatively, in a case where transparency is not necessary, it ispreferred to use an electrically-conductive material with a low workfunction (e.g., ϕ=3.5 eV to 4.5 eV) as an electrically-conductivematerial to be included in the cathode which functions as an electrodefor extracting electrons. Specifically, examples of such anelectrically-conductive material include alkali metal (e.g., Li, Na, K,and the like) and fluorides or oxides thereof, alkaline earth metal(e.g., Mg, Ca, and the like) and fluorides or oxides thereof, aluminum(Al), zinc (Zn), tin (Sn), thallium (Tl), a sodium-potassium alloy, analuminum-lithium alloy, a magnesium-silver alloy, indium, rare earthmetal such as ytterbium, and alloys thereof. Alternatively, examples ofthe material to be included in the cathode includeelectrically-conductive materials, including metal such as platinum(Pt), gold (Au), palladium (Pd), chromium (Cr), nickel (Ni), silver(Ag), tantalum (Ta), tungsten. (W), copper (Cu), titanium (Ti), iron(Fe), cobalt (Co), or molybdenum (Mo), alloys including these metalelements, electrically-conductive particles including these metals,electrically-conductive particles of alloys containing these metals,polysilicon including impurities, carbon materials, oxide semiconductormaterials, carbon nanotubes, graphene, and the like, and stackedstructures of layers including these elements. Further examples of thematerial to be included in the cathode include organic materials(electrically-conductive polymers) such aspoly(3,4-ethylenedioxythiophene)/polystyrenesulfonic acid [PEDOT/PSS].In addition, these electrically-conductive materials may be mixed with abinder (polymer) into a paste or an ink, and the paste or the ink may becured and used as an electrode.

A dry method or a wet method is usable as a film-formation method forthe first electrode or the like and the second electrode (cathode oranode). Examples of the dry method include a physical vapor depositionmethod (PVD method) and a chemical vapor deposition method (CVD method).Examples of the film-formation method using the principle of the PVDmethod include a vacuum deposition method using resistance heating orradio frequency heating, an EB (electron beam) deposition method,various sputtering methods (magnetron sputtering method, RF-DC coupledbias sputtering method, ECR sputtering method, facing-target sputteringmethod, and high frequency sputtering method), an ion plating method, alaser ablation method, a molecular beam epitaxy method, and a lasertransfer method. In addition, examples of the CVD method include aplasma CVD method, a thermal CVD method, an organic metal (MO) CVDmethod, and an optical CVD method. Meanwhile, examples of the wet methodinclude an electrolytic plating method and an electroless platingmethod, a spin coating method, an ink jet method, a spray coatingmethod, a stamping method, a micro contact printing method, aflexographic printing method, an offset printing method, a gravureprinting method, a dipping method, etc. Examples of patterning methodsinclude chemical etching, including shadow mask, laser transfer,photolithography, and the like, and physical etching by ultravioletlight, laser, or the like. Examples of planarization techniques for thefirst electrode or the like and the second electrode include a laserplanarization method, a reflow method, a CMP (Chemical MechanicalPolishing) method, etc.

Examples of the material to be included in the insulating layer includenot only inorganic insulating materials exemplified by metal oxide highdielectric insulating materials including: silicon oxide-basedmaterials; silicon nitride (SiNy); and aluminum oxide (Al₂O₃), but alsoorganic insulating materials (organic polymers) exemplified bypolymethyl methacrylate (PMMA); polyvinyl phenol (PVP); polyvinylalcohol (PVA); polyimide; polycarbonate (PC); polyethylene terephthalate(PET); polystyrene; silanol derivatives (silane coupling agents)including N-2 (aminoethyl) 3-aminopropyltrimethoxysilane (AEAPTMS),3-mercaptopropyltrimethoxysilane (MPTMS), octadecyltrichlorosilane (OTS)and the like; novolac-type phenolic resins; fluoro resins;straight-chain hydrocarbons having a functional group being able to bondto the control electrode at one end, including octadecanethiol, dodecylisocyanate and the like, and combinations thereof. Examples of thesilicon oxide-based materials include silicon oxide (SiOx), BPSG, PSG,BSG, AsSG, PbSG, silicon oxynitride (SiON), SOG (spin-on-glass), and lowdielectric constant insulating materials (e.g., polyaryl ether,cycloperfluorocarbon polymers and benzocyclobutene, cyclic fluororesins, polytetrafluoroethylene, fluorinated aryl ether, fluorinatedpolyimide, amorphous carbon, and organic SOG). The insulating layer mayhave a single-layer configuration, or a configuration including aplurality of layers (e.g., two layers) stacked. In the latter case, aninsulating layer/lower layer may be formed at least over the chargeaccumulation electrode and in a region between the charge accumulationelectrode and the first electrode. A planarization process may beperformed on the insulating layer/lower layer to allow the insulatinglayer/lower layer to remain at least in the region between the chargeaccumulation electrode and the first electrode. It is sufficient that aninsulating layer/upper layer is formed over the remaining insulatinglayer/lower layer and the charge accumulation electrode. In this way, itis possible to planarize the insulating layer with reliability. It issufficient that materials forming the protection material layer, variousinterlayer insulating layers, and insulating material films areappropriately selected from these materials.

The configurations and structures of the floating diffusion layer, theamplification transistor, the reset transistor, and the selectiontransistor included in the control section may be similar to theconfigurations and structures of existing floating diffusion layers,amplification transistors, reset transistors, and selection transistors.The drive circuit may also have a well-known configuration andstructure.

While the first electrode is coupled to the floating diffusion layer anda gate section of the amplification transistor, it is sufficient that acontact hole section is formed for the coupling of the first electrodeto the floating diffusion layer and the gate section of theamplification transistor. Examples of a material for forming the contacthole section include polysilicon doped with impurities, a high meltingpoint metal and a metal silicide such as tungsten, Ti, Pt, Pd, Cu, TiW,TiN, TiNW, WSi₂, or MoSi₂, and a stacked structure of layers includingthese materials (e.g., Ti/TiN/W).

A first carrier blocking layer may be provided between the inorganicsemiconductor material layer and the first electrode, and a secondcarrier blocking layer may be provided between the organic photoelectricconversion layer and the second electrode. In addition, a first chargeinjection layer may be provided between the first carrier blocking layerand the first electrode, and a second charge injection layer may beprovided between the second carrier blocking layer and the secondelectrode. For example, examples of the materials to be included in theelectron injection layers include alkali metal, including lithium (Li),sodium (Na), and potassium (K), fluorides or oxides thereof, alkalineearth metal, including magnesium (Mg) and calcium (Ca), and fluorides oroxides thereof.

Examples of a film-formation method for various organic layers include adry film-forming method and a wet film-forming method. Examples of thedry film-forming method include a vacuum deposition method usingresistance heating, high frequency heating, or electron beam heating, aflash deposition method, a plasma deposition method, an EB depositionmethod, various sputtering methods (bipolar sputtering method, directcurrent sputtering method, direct current magnetron sputtering method,high frequency sputtering method, magnetron sputtering method, RF-DCcoupled bias sputtering method, ECR sputtering method, facing-targetsputtering method, high frequency sputtering method, and ion beamsputtering method), a DC (Direct Current) method, an RF method, amulti-cathode method, an activation reaction method, an electric fielddeposition method, various ion plating methods including ahigh-frequency ion plating method and a reactive ion plating method, alaser ablation method, a molecular beam epitaxy method, a laser transfermethod, and a molecular beam epitaxy (MBE) method. In addition, examplesof the CVD methods include a plasma CVD method, a thermal CVD method, anMOCVD method, and a photo CVD method. Meanwhile, specific examples ofthe wet method include a spin coating method; a dipping method; acasting method; a micro contact printing method; a drop casting method;various printing methods including a screen printing method, an ink jetprinting method, an offset printing method, a gravure printing method,and a flexographic printing method; a stamping method; a spray method;various coating methods including an air doctor coater method, a bladecoater method, a rod coater method, a knife coater method, a squeezecoater method, a reverse roll coater method, a transfer roll coatermethod, a gravure coater method, a kiss coater method, a cast coatermethod, a spray coater method, a slit orifice coater method, and acalendar coater method. Examples of a solvent in the coating methodinclude nonpolar or low polar organic solvents including toluene,chloroform, hexane, and ethanol. Examples of patterning methods includechemical etching including shadow mask, laser transfer,photolithography, and the like, and physical etching by ultravioletlight, laser, or the like. Examples of planarization techniques forvarious organic layers include a laser planarization method, a reflowmethod, etc.

As described above, the on-chip microlens and the light-blocking layermay be provided on the imaging element or the solid-state imaging deviceas necessary, and the drive circuit and wiring lines for driving theimaging element are provided. A shutter for controlling incidence oflight on the imaging element may be disposed as necessary, and anoptical cut filter may be provided according to the purpose of thesolid-state imaging device.

In addition, for the solid-state imaging devices of the first and secondconfigurations, a mode may be adopted in which one on-chip microlens isdisposed above one imaging element or the like of the presentdisclosure. Alternatively, a mode may be adopted in which two imagingelements or the like of the present disclosure constitute an imagingelement block, and one on-chip microlens is disposed above the imagingelement block.

For example, in a case of stacking the solid-state imaging device and areadout integrated circuit (ROIC), the stacking may be performed bylaying a driving substrate having the readout integrated circuit and aconnection section including copper (Cu) formed thereon and an imagingelement having a connection section formed thereon over each other suchthat their respective connection sections come into contact with eachother, and joining the connection sections. The connection sections maybe joined to each other using a solder bump or the like.

Further, a driving method for driving the solid-state imaging devicesaccording to the first and second aspects of the present disclosure maybe a driving method of the solid-state imaging device repeating thesteps of:

draining electric charge in the first electrodes out of the system allat once while accumulating electric charge in the inorganicsemiconductor material layers (alternatively, the inorganicsemiconductor material layers and the photoelectric conversion layers)in all of the imaging elements; and thereafter,

transferring the electric charge accumulated in the inorganicsemiconductor material layers (alternatively, the inorganicsemiconductor material layers and the photoelectric conversion layers)all at once to the first electrodes in all of the imaging elements, andafter completion of the transferring, sequentially reading out theelectric charge transferred to the first electrodes in the respectiveimaging elements.

In such a driving method of the solid-state imaging device, each imagingelement has a structure in which light having entered from side of thesecond electrode does not enter the first electrode and, in all of theimaging elements, electric charge in the first electrodes is drained outof the systems all at once while accumulating electric charge in theinorganic semiconductor material layers or the like. This makes itpossible to perform resetting of the first electrodes with reliabilityin all of the imaging elements simultaneously. Thereafter, in all of theimaging elements, the electric charge accumulated in the inorganicsemiconductor material layers or the like is transferred all at once tothe first electrodes, and after completion of the transferring, theelectric charge transferred to the first electrodes is sequentially readout in the respective imaging elements. It is therefore possible toachieve a so-called global shutter function easily.

A detailed description of the imaging element and the solid-stateimaging device of Example 1 is given below.

The imaging element 10 of Example 1 further includes a semiconductorsubstrate (more specifically, a silicon semiconductor layer) 70, and thephotoelectric conversion section is disposed above the semiconductorsubstrate 70. In addition, the imaging element 10 further includes thecontrol section provided in the semiconductor substrate 70 and includingthe drive circuit to which the first electrode 21 and the secondelectrode 22 are coupled. Here, a light incident surface of thesemiconductor substrate 70 is defined as above, and opposite side of thesemiconductor substrate 70 is defined as below. A wiring layer 62including a plurality of wiring lines is provided below thesemiconductor substrate 70.

At least a floating diffusion layer FD₁ and an amplification transistorTR1 _(amp) included in the control section are provided in thesemiconductor substrate 70, and the first electrode 21 is coupled to thefloating diffusion layer FD₁ and a gate section of the amplificationtransistor TR1 _(amp). A reset transistor TR1 _(rst) and a selectiontransistor TR1 _(sel) included in the control section are furtherprovided in the semiconductor substrate 70. The floating diffusion layerFD₁ is coupled to one of source/drain regions of the reset transistorTR1 _(rst). Another one of source/drain regions of the amplificationtransistor TR1 _(amp) is coupled to one of source/drain regions of theselection transistor TR1 _(sel). Another one of source/drain regions ofthe selection transistor TR1 _(sel) is coupled to a signal line VSL₁.The amplification transistor TR1 _(amp), the reset transistor TR1_(rst), and the selection transistor TR1 _(sel) constitute the drivecircuit.

Specifically, the imaging element and the stacked imaging element ofExample 1 are an imaging element and a stacked imaging element of theback illuminated type, and have a structure in which three imagingelements are stacked, the three imaging elements being: a green lightimaging element of Example 1 of a first type (hereinafter referred to asa “first imaging element”) having sensitivity to green light andincluding the green light photoelectric conversion layer of the firsttype for absorbing green light; an existing blue light imaging elementof a second type (hereinafter referred to as a “second imaging element”)having sensitivity to blue light and including the blue lightphotoelectric conversion layer of the second type for absorbing bluelight; and an existing red light imaging element of a second type(hereinafter referred to as a “third imaging element”) havingsensitivity to red light and including the red light photoelectricconversion layer of the second type for absorbing red light. Here, thered light imaging element (the third imaging element) 12 and the bluelight imaging element (the second imaging element) 11 are provided inthe semiconductor substrate 70, and the second imaging element 11 ispositioned closer to the light incident side than the third imagingelement 12. In addition, the green light imaging element (the firstimaging element 10) is provided above the blue light imaging element(the second imaging element 11). The stacked structure of the firstimaging element 10, the second imaging element 11, and the third imagingelement 12 constitutes one pixel. No color filter layer is provided.

In the first imaging element 10, the first electrode 21 and the chargeaccumulation electrode 24 are formed at a distance from each other on aninterlayer insulating layer 81. The interlayer insulating layer 81 andthe charge accumulation electrode 24 are covered with the insulatinglayer 82. The inorganic semiconductor material layer 23B and thephotoelectric conversion layer 23A are formed on the insulating layer82, and the second electrode 22 is formed on the photoelectricconversion layer 23A. A protection material layer 83 is formed over theentire surface inclusive of the second electrode 22, and an on-chipmicrolens 14 is provided on the protection material layer 83. No colorfilter layer is provided. The first electrode 21, the chargeaccumulation electrode 24, and the second electrode 22 are configured bytransparent electrodes including, for example, ITO (work function: about4.4 eV). The inorganic semiconductor material layer 23B includes, forexample, Al_(a1)Zn_(a2)Sn_(a3)O_(b1). The photoelectric conversion layer23A includes a layer including a known organic photoelectric conversionmaterial (e.g., an organic material such as rhodamine-based dye,merocyanine-based dye, or quinacridone) having sensitivity to at leastgreen light. The interlayer insulating layer 81, the insulating layer82, and the protection material layer 83 include a known insulatingmaterial (e.g., SiO₂ or SiN). The inorganic semiconductor material layer23B and the first electrode 21 are coupled to each other by a connectionsection 67 provided at the insulating layer 82. The inorganicsemiconductor material layer 23B extends in the connection section 67.That is, the inorganic semiconductor material layer 23B extends in anopening 84 provided in the insulating layer 82, and is coupled to thefirst electrode 21.

The charge accumulation electrode 24 is coupled to the drive circuit.Specifically, the charge accumulation electrode 24 is coupled to avertical drive circuit 112 included in the drive circuit, via aconnection hole 66, a pad section 64, and a wiring line V_(OA) providedin the interlayer insulating layer 81.

The charge accumulation electrode 24 is larger in size than the firstelectrode 21. Although not limited, it is preferred to satisfy:

4 ≤ s₁^(′)/s₁

where s₁′ denotes the area of the charge accumulation electrode 24, ands₁ denotes the area of the first electrode 21. For example, in Example1,

s₁^(′)/s₁ = 8,

holds true, although not limited thereto.

Element separation regions 71 are formed on side of a first surface(front surface) 70A of the semiconductor substrate 70, and an oxide film72 is formed over the first surface 70A of the semiconductor substrate70. Further, on side of the first surface of the semiconductor substrate70, the reset transistor TR1 _(rst), the amplification transistor TR1_(amp), and the selection transistor TR1 _(sel) included in the controlsection of the first imaging element 10 are provided, and further, thefirst floating diffusion layer FD₁ is provided.

The reset transistor TR1 _(rst) includes a gate section 51, a channelformation region 51A, and source/drain regions 51B and 51C. The gatesection 51 of the reset transistor TR1 _(rst) is coupled to a reset lineRST₁, the one source/drain region 51C of the reset transistor TR1 _(rst)also serves as the first floating diffusion layer FD₁, and anothersource/drain region 51B is coupled to a power supply V_(DD).

The first electrode 21 is coupled to the one source/drain region 51C(the first floating diffusion layer FD₁) of the reset transistor TR1_(rst), via a connection hole 65 and a pad section 63 provided in theinterlayer insulating layer 81, and a contact hole section 61 formed inthe semiconductor substrate 70 and an interlayer insulating layer 76,and the wiring layer 62 formed in the interlayer insulating layer 76.

The amplification transistor TR1 _(amp) includes a gate section 52, achannel formation region 52A, and source/drain regions 52B and 52C. Thegate section 52 is coupled to the first electrode 21 and the onesource/drain region 51C (the first floating diffusion layer FD₁) of thereset transistor TR1 _(rst) via the wiring layer 62. In addition, theone source/drain region 52B is coupled to the power supply V_(DD).

The selection transistor TR1 _(sel) includes a gate section 53, achannel formation region 53A, and source/drain regions 53B and 53C. Thegate section 53 is coupled to a selection line SEL₁. In addition, theone source/drain region 53B shares a region with another source/drainregion 52C included in the amplification transistor TR1 _(amp), andanother source/drain region 53C is coupled to a signal line (data outputline) VSL₁ (117).

The second imaging element 11 includes an n-type semiconductor region 41provided in the semiconductor substrate 70, as a photoelectricconversion layer. A gate section 45 of a transfer transistor TR2 _(trs)including a vertical transistor extends to the n-type semiconductorregion 41, and is coupled to a transfer gate line TG₂. In addition, asecond floating diffusion layer FD₂ is provided in a region 45C of thesemiconductor substrate 70 in the vicinity of the gate section 45 of thetransfer transistor TR2 _(trs). Electric charge accumulated in then-type semiconductor region 41 is read out to the second floatingdiffusion layer FD₂ via a transfer channel formed along the gate section45.

In the second imaging element 11, further, a reset transistor TR2_(rst), an amplification transistor TR2 _(amp), and a selectiontransistor TR2 _(sel) included in the control section of the secondimaging element 11 are provided on the side of the first surface of thesemiconductor substrate 70.

The reset transistor TR2 _(rst) includes a gate section, a channelformation region, and source/drain regions. The gate section of thereset transistor TR2 _(rst) is coupled to a reset line RST₂, one of thesource/drain regions of the reset transistor TR2 _(rst) is coupled tothe power supply V_(DD), and another one of the source/drain regionsalso serves as the second floating diffusion layer FD₂.

The amplification transistor TR2 _(amp) includes a gate section, achannel formation region, and source/drain regions. The gate section iscoupled to another one of the source/drain regions (the second floatingdiffusion layer FD₂) of the reset transistor TR2 _(rst). In addition,one of the source/drain regions is coupled to the power supply V_(DD).

The selection transistor TR2 _(sel) includes a gate section, a channelformation region, and source/drain regions. The gate section is coupledto a selection line SEL₂. In addition, one of the source/drain regionsshares a region with another one of the source/drain regions included inthe amplification transistor TR2 _(amp), and the other one of thesource/drain regions is coupled to a signal line (data output line)VSL₂.

The third imaging element 12 includes an n-type semiconductor region 43provided in the semiconductor substrate 70, as a photoelectricconversion layer. Agate section 46 of a transfer transistor TR3 _(trs)is coupled to a transfer gate line TG₃. In addition, a third floatingdiffusion layer FD₃ is provided in a region 46C of the semiconductorsubstrate 70 in the vicinity of the gate section 46 of the transfertransistor TR3 _(trs). Electric charge accumulated in the n-typesemiconductor region 43 is read out to the third floating diffusionlayer FD₃ via a transfer channel 46A formed along the gate section 46.

In the third imaging element 12, further, a reset transistor TR3 _(rst),an amplification transistor TR3 _(amp), and a selection transistor TR3_(sel) included in the control section of the third imaging element 12are provided on the side of the first surface of the semiconductorsubstrate 70.

The reset transistor TR3 _(rst) includes a gate section, a channelformation region, and source/drain regions. The gate section of thereset transistor TR3 _(rst) is coupled to a reset line RST₃, one of thesource/drain regions of the reset transistor TR3 _(rst) is coupled tothe power supply V_(DD), and another one of the source/drain regionsalso serves as the third floating diffusion layer FD₃.

The amplification transistor TR3 _(amp) includes a gate section, achannel formation region, and source/drain regions. The gate section iscoupled to the other one of the source/drain regions (the third floatingdiffusion layer FD₃) of the reset transistor TR3 _(rst). In addition,one of the source/drain regions is coupled to the power supply V_(DD).

The selection transistor TR3 _(sel) includes a gate section, a channelformation region, and source/drain regions. The gate section is coupledto a selection line SEL₃. In addition, one of the source/drain regionsshares a region with another one of the source/drain regions included inthe amplification transistor TR3 _(amp), and another one of thesource/drain regions is coupled to a signal line (data output line)VSL₃.

The reset lines RST₁, RST₂, and RST₃, the selection lines SEL₁, SEL₂,and SEL₃, and the transfer gate lines TG₂ and TG₃ are coupled to thevertical drive circuit 112 included in the drive circuit. The signallines (data output lines) VSL₁, VSL₂, and VSL₃ are coupled to a columnsignal processing circuit 113 included in the drive circuit.

A p⁺ layer 44 is provided between the n-type semiconductor region 43 andthe front surface 70A of the semiconductor substrate 70, and suppressesgeneration of a dark current. A p⁺ layer 42 is formed between the n-typesemiconductor region 41 and the n-type semiconductor region 43, andfurther, a portion of a side surface of the n-type semiconductor region43 is surrounded by the p⁺ layer 42. A p⁺ layer 73 is formed on side ofa back surface 70B of the semiconductor substrate 70, and an HfO₂ film74 and an insulating material film 75 are formed in a region extendingfrom the p⁺ layer 73 to a part inside of the semiconductor substrate 70where the contact hole section 61 is to be formed. While wiring linesare formed across a plurality of layers in the interlayer insulatinglayer 76, illustrations thereof are omitted.

The HfO₂ film 74 is a film having a negative fixed charge. By providingsuch a film, it is possible to suppress generation of a dark current.The HfO₂ film may be replaced with an aluminum oxide (Al₂O₃) film, azirconium oxide (ZrO₂) film, a tantalum oxide (Ta₂O₅) film, a titaniumoxide (TiO₂) film, a lanthanum oxide (La₂O₃) film, a praseodymium oxide(Pr₂O₃) film, a cerium oxide (CeO₂) film, a neodymium oxide (Nd₂O₃)film, a promethium oxide (Pm₂O₃) film, a samarium oxide (Sm₂O₃) film, aneuropium oxide (Eu₂O₃) film, a gadolinium oxide ((Gd₂O₃) film, a terbiumoxide (Tb₂O₃) film, a dysprosium oxide (Dy₂O₃) film, a holmium oxide(H₀₂O₃) film, a thulium oxide (Tm₂O₃) film, a ytterbium oxide (Yb₂O₃)film, a lutetium oxide (Lu₂O₃) film, a yttrium oxide (Y₂O₃) film, ahafnium nitride film, an aluminum nitride film, a hafnium oxynitridefilm, or an aluminum oxynitride film. Examples of the film-formingmethod for these films include a CVD method, a PVD method, and an ALDmethod.

In the following, description is given of an operation of the stackedimaging element (the first imaging element 10) including the chargeaccumulation electrode of Example 1 with reference to FIGS. 5 and 6A.The imaging element of Example 1 further includes a control sectionprovided in the semiconductor substrate 70 and including a drivecircuit. The first electrode 21, the second electrode 22, and the chargeaccumulation electrode 24 are coupled to the drive circuit. Here, thepotential of the first electrode 21 is made higher than the potential ofthe second electrode 22. That is, for example, the first electrode 21 isset to a positive potential and the second electrode 22 is set to anegative potential. Then, electrons generated by photoelectricconversion in the photoelectric conversion layer 23A are read out to thefloating diffusion layer. The same applies also to other examples.

Reference numerals used in FIG. 5; FIGS. 20 and 21 in Example 4described later; and FIGS. 32 and 33 in Example 6 are as follows.

P_(A): Potential at point P_(A) in a region of the inorganicsemiconductor material layer 23B opposed to a region positionedintermediate between the charge accumulation electrode 24 or a transfercontrol electrode (charge transfer electrode) 25 and the first electrode21P_(B): Potential at point P_(B) in a region of the inorganicsemiconductor material layer 23B opposed to the charge accumulationelectrode 24P_(C1): Potential at point P_(C1) in a region of the inorganicsemiconductor material layer 23B opposed to a charge accumulationelectrode segment 24AP_(C2): Potential at point P_(C2) in a region of the inorganicsemiconductor material layer 23B opposed to a charge accumulationelectrode segment 24BP_(C3): Potential at point P_(C3) in a region of the inorganicsemiconductor material layer 23B opposed to a charge accumulationelectrode segment 24CP_(D): Potential at point P_(D) in a region of the inorganicsemiconductor material layer 23B opposed to the transfer controlelectrode (charge transfer electrode) 25FD: Potential at the first floating diffusion layer FD₁V_(OA): Potential at the charge accumulation electrode 24V_(OA-A): Potential at the charge accumulation electrode segment 24AV_(OA-B): Potential at the charge accumulation electrode segment 24BV_(OA-C): Potential at the charge accumulation electrode segment 24CV_(OT): Potential at the transfer control electrode (charge transferelectrode) 25RST: Potential at the gate section 51 of the reset transistor TR1 _(rst)V_(DD): Potential of the power supplyVSL₁: Signal line (data output line) VSL₁TR1 _(rst): Reset transistor TR1 _(rst)TR1 _(amp): Amplification transistor TR1 _(amp)TR1 _(sel): Selection transistor TR1 _(sel)

During a charge accumulation period, from the drive circuit, thepotential V₁₁ is applied to the first electrode 21 and the potential V₃₁is applied to the charge accumulation electrode 24. Light having enteredthe photoelectric conversion layer 23A generates photoelectricconversion in the photoelectric conversion layer 23A. Holes generated bythe photoelectric conversion are sent from the second electrode 22 tothe drive circuit via a wiring line V_(OU). Meanwhile, because thepotential of the first electrode 21 is higher than the potential of thesecond electrode 22, i.e., because a positive potential is to be appliedto the first electrode 21 and a negative potential is to be applied tothe second electrode 22, V₃₁≥V₁₁ holds true, and preferably, V₃₁>V₁₁holds true. This causes electrons generated by the photoelectricconversion to be attracted to the charge accumulation electrode 24, andto remain in a region of the inorganic semiconductor material layer 23B,or the inorganic semiconductor material layer 23B and the photoelectricconversion layer 23A (hereinafter, these layers are collectivelyreferred to as an “inorganic semiconductor material layer 23B or thelike”), opposed to the charge accumulation electrode 24. That is,electric charge is accumulated in the inorganic semiconductor materiallayer 23B or the like. Because V₃₁>V₁₁ holds true, the electronsgenerated inside of the photoelectric conversion layer 23A would notmove toward the first electrode 21. With the passage of time ofphotoelectric conversion, the potential in the region of the inorganicsemiconductor material layer 23B or the like opposed to the chargeaccumulation electrode 24 has a more negative value.

A reset operation is performed later in the charge accumulation period.This resets the potential of the first floating diffusion layer FD₁, andthe potential of the first floating diffusion layer FD₁ shifts to thepotential V_(DD) of the power supply.

After completion of the reset operation, the electric charge is readout. That is, during a charge transfer period, from the drive circuit,the potential V₁₂ is applied to the first electrode 21 and the potentialV₃₂ is applied to the charge accumulation electrode 24. Here, V₃₂<V₁₂holds true. This causes the electrons remaining in the region of theinorganic semiconductor material layer 23B or the like opposed to thecharge accumulation electrode 24 to be read out to the first electrode21, and further to the first floating diffusion layer FD₁. That is, theelectric charge accumulated in the inorganic semiconductor materiallayer 23B or the like is read out to the control section.

This completes the series of operations including the chargeaccumulation, the reset operation, and the charge transfer.

The operations of the amplification transistor TR1 _(amp) and theselection transistor TR1 _(sel) after the electrons are read out to thefirst floating diffusion layer FD₁ are the same as the operations ofexisting ones of these transistors. In addition, the series ofoperations including the charge accumulation, the reset operation, andthe charge transfer of the second imaging element 11 and the thirdimaging element 12 are similar to the series of operations including thecharge accumulation, the reset operation, and the charge transferaccording to existing techniques. In addition, reset noise of the firstfloating diffusion layer FD₁ is removable through a correlated doublesampling (CDS, Correlated Double Sampling) process in a similar mannerto the existing techniques.

As has been described, in Example 1, the charge accumulation electrodeis provided that is disposed at a distance from the first electrode anddisposed to be opposed to the photoelectric conversion layer with theinsulating layer interposed therebetween. Thus, when the photoelectricconversion layer is irradiated with light and photoelectric conversionoccurs in the photoelectric conversion layer, a kind of capacitor isformed by the inorganic semiconductor material layer or the like, theinsulating layer, and the charge accumulation electrode, making itpossible to accumulate electric charge in the inorganic semiconductormaterial layer or the like. For this reason, at the time of start ofexposure, it is possible to completely deplete the charge accumulationsection to thereby eliminate the electric charge. As a result, it ispossible to suppress the occurrence of a phenomenon in which kTC noisebecomes greater and random noise deteriorates to cause reduction inquality of the captured images. In addition, because it is possible toreset all of the pixels all at once, the so-called global shutterfunction is achievable.

FIG. 68 illustrates a conceptual diagram of the solid-state imagingdevice of Example 1. The solid-state imaging device 100 of Example 1includes an imaging region 111 in which stacked imaging elements 101 arearranged in a two-dimensional array, and, as drive circuits (peripheralcircuits) thereof, the vertical drive circuit 112, the column signalprocessing circuit 113, a horizontal drive circuit 114, an outputcircuit 115, a drive control circuit 116, and the like. Needless to say,these circuits may be configured of known circuits, or may be configuredusing other circuit configurations (e.g., various circuits used inexisting CCD imaging devices or CMOS imaging devices). In FIG. 68, therepresentation of a reference numeral “101” for the stacked imagingelements 101 is made in only one row.

On the basis of a vertical synchronization signal, a horizontalsynchronization signal, and a master clock, the drive control circuit116 generates a clock signal and a control signal serving as a referencefor operations of the vertical drive circuit 112, the column signalprocessing circuit 113, and the horizontal drive circuit 114. Then, theclock signal and the control signal thus generated are inputted to thevertical drive circuit 112, the column signal processing circuit 113,and the horizontal drive circuit 114.

The vertical drive circuit 112 includes, for example, a shift register,and selectively scans the stacked imaging elements 101 in the imagingregion 111 sequentially in the vertical direction row by row. Then, apixel signal (image signal) based on a current (signal) generatedaccording to the amount of light reception at each stacked imagingelement 101 is sent to the column signal processing circuit 113 via thesignal line (data output line) 117 or VSL.

The column signal processing circuit 113 is disposed, for example, foreach column of the stacked imaging elements 101, and performs signalprocessing, including noise removal and signal amplification, on theimage signals outputted from one row of the stacked imaging elements 101for each imaging element in accordance with a signal from a blackreference pixel (although not illustrated, formed around the effectivepixel region). At an output stage of the column signal processingcircuit 113, a horizontal selection switch (not illustrated) is providedto be coupled between the output stage and a horizontal signal line 118.

The horizontal drive circuit 114 includes, for example, a shiftregister, and sequentially outputs horizontal scan pulses tosequentially select each one of the column signal processing circuits113, thereby outputting a signal from each of the column signalprocessing circuits 113 to the horizontal signal line 118.

The output circuit 115 performs signal processing on the signalssequentially supplied from the respective column signal processingcircuits 113 through the horizontal signal line 118, and outputs theprocessed signals.

FIG. 9 is an equivalent circuit diagram of a modification example of theimaging element and the stacked imaging element of Example 1, and FIG.10 is a schematic layout diagram of the first electrode, the chargeaccumulation electrode, and the transistors included in the controlsection. As illustrated, the other source/drain region 51B of the resettransistor TR1 _(rst) may be grounded, instead of being coupled to thepower supply V_(DD).

It is possible to produce the imaging element and stacked imagingelement of Example 1 by the following method, for example. That is, anSOI substrate is prepared first. A first silicon layer is then formed onthe surface of the SOI substrate on the basis of an epitaxial growthmethod, and the p⁺ layer 73 and the n-type semiconductor region 41 areformed on the first silicon layer. Next, a second silicon layer isformed on the first silicon layer on the basis of an epitaxial growthmethod, and the element separation region 71, the oxide film 72, the p⁺layer 42, the n-type semiconductor region 43, and the p⁺ layer 44 areformed on the second silicon layer. In addition, various transistors andthe like included in the control section of the imaging element areformed on the second silicon layer, and the wiring layer 62, theinterlayer insulating layer 76, and various wiring lines are furtherformed thereon. The interlayer insulating layer 76 and a supportsubstrate (not illustrated) are thereafter bonded to each other.Thereafter, the SOI substrate is removed to expose the first siliconlayer. The surface of the second silicon layer corresponds to the frontsurface 70A of the semiconductor substrate 70, and the surface of thefirst silicon layer corresponds to the back surface 70B of thesemiconductor substrate 70. In addition, the first silicon layer and thesecond silicon layer are collectively expressed as the semiconductorsubstrate 70. Next, an opening for forming the contact hole section 61is formed on the side of the back surface 70B of the semiconductorsubstrate 70, and the HfO₂ film 74, the insulating material film 75, andthe contact hole section 61 are formed. Further, the pad sections 63 and64, the interlayer insulating layer 81, the connection holes 65 and 66,the first electrode 21, the charge accumulation electrode 24, and theinsulating layer 82 are formed. Next, the connection section 67 isopened, and the inorganic semiconductor material layer 23B, thephotoelectric conversion layer 23A, the second electrode 22, theprotection material layer 83, and the on-chip microlens 14 are formed.It is possible to obtain the imaging element and the stacked imagingelement of Example 1 in the above-described manner.

In addition, although not illustrated, the insulating layer 82 may havea two-layer configuration including an insulating layer or lower layerand an insulating layer or upper layer. That is, it is sufficient thatthe insulating layer or lower layer is formed at least over the chargeaccumulation electrode 24 and in a region between the chargeaccumulation electrode 24 and the first electrode 21 (more specifically,the insulating layer or lower layer may be formed on the interlayerinsulating layer 81 including the charge accumulation electrode 24), aplanarization process is performed on the insulating layer or lowerlayer, and thereafter, the insulating layer or upper layer is formedover the insulating layer or lower layer and the charge accumulationelectrode 24. This makes it possible to accomplish the planarization ofthe insulating layer 82 with reliability. It is then sufficient that theconnection section 67 is opened in the insulating layer 82 obtained inthis way.

Example 2

Example 2 is a modification of Example 1. FIG. 11 is a schematic partialcross-sectional view of an imaging element and a stacked imaging elementof Example 2. The imaging element and the stacked imaging element ofExample 2 are of the front illuminated type, and have a structure inwhich three imaging elements are stacked, the three imaging elementsbeing: the green light imaging element of Example 1 of the first type(the first imaging element 10) having sensitivity to green light andincluding the green light photoelectric conversion layer of the firsttype for absorbing green light; the existing blue light imaging elementof the second type (the second imaging element 11) having sensitivity toblue light and including the blue light photoelectric conversion layerof the second type for absorbing blue light; and the existing red lightimaging element of the second type (the third imaging element 12) havingsensitivity to red light and including the red light photoelectricconversion layer of the second type for absorbing red light. Here, thered light imaging element (the third imaging element 12) and the bluelight imaging element (the second imaging element 11) are provided inthe semiconductor substrate 70, and the second imaging element 11 ispositioned closer to the light incident side than the third imagingelement 12. In addition, the green light imaging element (the firstimaging element 10) is provided above the blue light imaging element(the second imaging element 11).

As in Example 1, various transistors included in the control section areprovided on side of the front surface 70A of the semiconductor substrate70. These transistors may have configurations and structuressubstantially similar to those of the transistors described inExample 1. In addition, while the second imaging element 11 and thethird imaging element 12 are provided in the semiconductor substrate 70,these imaging elements may also have configurations and structuressubstantially similar to those of the second imaging element 11 and thethird imaging element 12 described in Example 1.

The interlayer insulating layer 81 is formed above the front surface 70Aof the semiconductor substrate 70, and the first electrode 21, theinorganic semiconductor material layer 23B, the photoelectric conversionlayer 23A, and the second electrode 22, and also the charge accumulationelectrode 24, etc. are provided above the interlayer insulating layer81, as in the imaging element of Example 1.

In this way, it is possible for the imaging element and the stackedimaging element of Example 2 to have configurations and structuressimilar to the configurations and structures of the imaging element andthe stacked imaging element of Example 1, except for being of the frontilluminated type, and the detailed description thereof is thus omitted.

Example 3

Example 3 is a modification of Example 1 and Example 2.

FIG. 12 is a schematic partial cross-sectional view of an imagingelement and a stacked imaging element of Example 3. The imaging elementand the stacked imaging element of Example 3 are of the back illuminatedtype, and have a structure in which two imaging elements are stacked,the two imaging elements being the first imaging element 10 of Example 1of the first type and the third imaging element 12 of the second type.In addition, FIG. 13 is a schematic partial cross-sectional view of amodification example of the imaging element and the stacked imagingelement of Example 3. The modification example of the imaging elementand the stacked imaging element of Example 3 are of the frontilluminated type, and has a structure in which two imaging elements arestacked, the two imaging elements being the first imaging element 10 ofExample 1 of the first type and the third imaging element 12 of thesecond type. Here, the first imaging element 10 absorbs light in primarycolors, and the third imaging element 12 absorbs light in complementarycolors. Alternatively, the first imaging element 10 absorbs white light,and the third imaging element 12 absorbs infrared rays.

FIG. 14 is a schematic partial cross-sectional view of a modificationexample of the imaging element of Example 3. The modification example ofthe imaging element of Example 3 is of the back illuminated type, andincludes the first imaging element 10 of Example 1 of the first type. Inaddition, FIG. 15 is a schematic partial sectional view of amodification example of the imaging element of Example 3. Themodification example of the imaging element of Example 3 is of the frontilluminated type, and includes the first imaging element 10 of Example 1of the first type. Here, the first imaging element 10 includes threekinds of imaging elements, i.e., an imaging element that absorbs redlight, an imaging element that absorbs green light, and an imagingelement that absorbs blue light. Further, a plurality of ones of theseimaging elements are included in the solid-state imaging deviceaccording to the first aspect of the present disclosure. Examples ofarrangement of the plurality of ones of these imaging elements include aBayer arrangement. Color filter layers for performing blue, green, andred spectral separation are disposed on the light incident side of theimaging elements as necessary.

Instead of providing one imaging element of Example 1 of the first type,two may be provided in a stacked mode (i.e., a mode in which twophotoelectric conversion sections are stacked, and control sections forthe two photoelectric conversion sections are provided in thesemiconductor substrate), or alternatively, three may be provided in astacked mode (i.e., a mode in which three photoelectric conversionsections may be stacked, and control sections for the threephotoelectric conversion sections are provided in the semiconductorsubstrate). The following table illustrates examples of the stackedstructures of the imaging element of the first type and the imagingelement of the second type.

First type Second type Back illuminated 1 2 type and front Green Blue +Red illuminated 1 1 type Primary color Complementary color 1 1 WhiteInfrared 1 0 Blue, Green, or Red 2 2 Green + Infrared Blue + Red 2 1Green + Blue Red 2 0 White + Infrared 3 2 Green + Blue + Red Blue-Green(Emerald) + Infrared 3 1 Green + Blue + Red Infrared 3 0 Blue + Green +Red

Example 4

Example 4 is a modification of Examples 1 to 3, and relates to animaging element or the like including the transfer control electrode(charge transfer electrode) of the present disclosure. FIG. 16 is aschematic partial cross-sectional view of a portion of an imagingelement and a stacked imaging element of Example 4. FIGS. 17 and 18 areequivalent circuit diagrams of the imaging element and the stackedimaging element of Example 4. FIG. 19 is a schematic layout diagram ofthe first electrode, the transfer control electrode, and the chargeaccumulation electrode, and transistors included in the control sectionthat are included in the imaging element of Example 4. FIGS. 20 and 21schematically illustrate a state of potentials at each part duringoperation of the imaging element of Example 4. FIG. 6B is an equivalentcircuit diagram for describing each part of the imaging element ofExample 4. In addition, FIG. 22 is a schematic layout diagram of thefirst electrode, the transfer control electrode, and the chargeaccumulation electrode included in the photoelectric conversion sectionof the imaging element of Example 4. FIG. 23 is a schematic transparentperspective view of the first electrode, the transfer control electrode,the charge accumulation electrode, the second electrode, and the contacthole section.

The imaging element and the stacked imaging element of Example 4 furtherinclude, between the first electrode 21 and the charge accumulationelectrode 24, the transfer control electrode (charge transfer electrode)25 disposed at a distance from the first electrode 21 and the chargeaccumulation electrode 24, and disposed to be opposed to the inorganicsemiconductor material layer 23B with the insulating layer 82 interposedtherebetween. The transfer control electrode 25 is coupled to a pixeldrive circuit included in the drive circuit, via a connection hole 68B,a pad section 68A, and a wiring line V_(OT) provided in the interlayerinsulating layer 81.

In the following, description is given of an operation of the imagingelement (the first imaging element 10) of Example 4 with reference toFIGS. 20 and 21. It is to be noted that, in FIGS. 20 and 21, the valuesof a potential to be applied to the charge accumulation electrode 24 anda potential at point P_(D) are different.

During a charge accumulation period, from the drive circuit, thepotential V₁₁ is applied to the first electrode 21, the potential V₃₁ isapplied to the charge accumulation electrode 24, and the potential V₅₁is applied to the transfer control electrode 25. Light having enteredthe photoelectric conversion layer 23A generates photoelectricconversion in the photoelectric conversion layer 23A. Holes generated bythe photoelectric conversion are sent from the second electrode 22 tothe drive circuit via the wiring line V_(OU). Meanwhile, the potentialof the first electrode 21 is higher than the potential of the secondelectrode 22, i.e., for example, a positive potential is to be appliedto the first electrode 21 and a negative potential is to be applied tothe second electrode 22. Thus, V₃₁>V₅₁ (e.g., V₃₁>V₁₁>V₅₁, orV₁₁>V₃₁>V₅₁) holds true. This causes electrons generated by thephotoelectric conversion to be attracted to the charge accumulationelectrode 24, and to remain in the region of the inorganic semiconductormaterial layer 23B or the like opposed to the charge accumulationelectrode 24. That is, electric charge is accumulated in the inorganicsemiconductor material layer 23B or the like. Because V₃₁>V₅₁ holdstrue, it is possible to prevent, with reliability, the electronsgenerated inside of the photoelectric conversion layer 23A from movingtoward the first electrode 21. With the passage of time of photoelectricconversion, the potential in the region of the inorganic semiconductormaterial layer 23B or the like opposed to the charge accumulationelectrode 24 has a more negative value.

A reset operation is performed later in the charge accumulation period.This resets the potential of the first floating diffusion layer FD₁, andthe potential of the first floating diffusion layer FD₁ shifts to thepotential V_(DD) of the power supply.

After completion of the reset operation, the electric charge is readout. That is, during a charge transfer period, from the drive circuit,the potential V₁₂ is applied to the first electrode 21, the potentialV₃₂ is applied to the charge accumulation electrode 24, and thepotential V₅₂ is applied to the transfer control electrode 25. Here,V₃₂≤V₅₂≤V₁₂ (preferably, V₃₂<V₅₂<V₁₂) holds true. This causes theelectrons remaining in the region of the inorganic semiconductormaterial layer 23B or the like opposed to the charge accumulationelectrode 24 to be read out to the first electrode 21, and further tothe first floating diffusion layer FD₁ with reliability. That is, theelectric charge accumulated in the inorganic semiconductor materiallayer 23B or the like is read out to the control section.

This completes the series of operations including the chargeaccumulation, the reset operation, and the charge transfer.

The operations of the amplification transistor TR1 _(amp) and theselection transistor TR1 _(sel) after the electrons are read out to thefirst floating diffusion layer FD₁ are the same as the operations ofexisting ones of these transistors. In addition, for example, the seriesof operations including the charge accumulation, the reset operation,and the charge transfer of the second imaging element 11 and the thirdimaging element 12 are similar to the series of operations including thecharge accumulation, the reset operation, and the charge transferaccording to existing techniques.

FIG. 24 is a schematic layout diagram of the first electrode and thecharge accumulation electrode, and the transistors included in thecontrol section that are included in a modification example of theimaging element of Example 4. As illustrated, the other source/drainregion 51B of the reset transistor TR1 _(rst) may be grounded, insteadof being coupled to the power supply V_(DD).

Example 5

Example 5 is a modification of Examples 1 to 4, and relates to animaging element or the like including the charge drain electrode of thepresent disclosure. FIG. 25 is a schematic partial cross-sectional viewof a portion of an imaging element of Example 5. FIG. 26 is a schematiclayout diagram of the first electrode, the charge accumulationelectrode, and the charge drain electrode included in the photoelectricconversion section including the charge accumulation electrode of theimaging element of Example 5. FIG. 27 is a schematic transparentperspective view of the first electrode, the charge accumulationelectrode, the charge drain electrode, the second electrode, and thecontact hole section.

The imaging element of Example 5 further includes a charge drainelectrode 26 coupled to the inorganic semiconductor material layer 23Bvia a connection section 69 and disposed at a distance from the firstelectrode 21 and the charge accumulation electrode 24. Here, the chargedrain electrode 26 is disposed to surround the first electrode 21 andthe charge accumulation electrode 24 (i.e., in a picture frame form).The charge drain electrode 26 is coupled to the pixel drive circuitincluded in the drive circuit. The inorganic semiconductor materiallayer 23B extends in the connection section 69. That is, the inorganicsemiconductor material layer 23B extends in a second opening 85 providedin the insulating layer 82, and the inorganic semiconductor materiallayer 23B is coupled to the charge drain electrode 26. The charge drainelectrode 26 is shared by (common to) a plurality of imaging elements. Aside surface of the second opening 85 may be sloped to widen the secondopening 85 upward. The charge drain electrode 26 is usable as, forexample, a floating diffusion or overflow drain of the photoelectricconversion section.

In Example 5, during a charge accumulation period, from the drivecircuit, the potential V₁₁ is applied to the first electrode 21, thepotential V₃₁ is applied to the charge accumulation electrode 24, thepotential V₆₁ is applied to the charge drain electrode 26, and electriccharge is accumulated in the inorganic semiconductor material layer 23Bor the like. Light having entered the photoelectric conversion layer 23Agenerates photoelectric conversion in the photoelectric conversion layer23A. Holes generated by the photoelectric conversion are sent from thesecond electrode 22 to the drive circuit via the wiring line V_(OU).Meanwhile, the potential of the first electrode 21 is higher than thepotential of the second electrode 22, i.e., for example, a positivepotential is to be applied to the first electrode 21 and a negativepotential is to be applied to the second electrode 22. Thus, V₆₁>V₁₁(e.g., V₃₁>V₆₁>V₁₁) holds true. This causes electrons generated by thephotoelectric conversion to be attracted to the charge accumulationelectrode 24, and to remain in the region of the inorganic semiconductormaterial layer 23B or the like opposed to the charge accumulationelectrode 24. It is thus possible to prevent, with reliability, theelectrons from moving toward the first electrode 21. However, electronsthat are not sufficiently attracted by the charge accumulation electrode24 or that have failed to be accumulated in the inorganic semiconductormaterial layer 23B or the like (so-called overflowing electrons) aresent to the drive circuit via the charge drain electrode 26.

A reset operation is performed later in the charge accumulation period.This resets the potential of the first floating diffusion layer FD₁, andthe potential of the first floating diffusion layer FD₁ shifts to thepotential V_(DD) of the power supply.

After completion of the reset operation, the electric charge is readout. That is, during a charge transfer period, from the drive circuit,the potential V₁₂ is applied to the first electrode 21, the potentialV₃₂ is applied to the charge accumulation electrode 24, and thepotential V₆₂ is applied to the charge drain electrode 26. Here, V₆₂<V₁₂(e.g., V₆₂<V₃₂<V₁₂) holds true. This causes the electrons remaining inthe region of the inorganic semiconductor material layer 23B or the likeopposed to the charge accumulation electrode 24 to be read out to thefirst electrode 21, and further to the first floating diffusion layerFD₁ with reliability. That is, the electric charge accumulated in theinorganic semiconductor material layer 23B or the like is read out tothe control section.

This completes the series of operations including the chargeaccumulation, the reset operation, and the charge transfer.

The operations of the amplification transistor TR1 _(amp) and theselection transistor TR1 _(sel) after the electrons are read out to thefirst floating diffusion layer FD₁ are the same as the operations ofexisting ones of these transistors. In addition, for example, the seriesof operations including the charge accumulation, the reset operation,and the charge transfer of the second imaging element and the thirdimaging element are similar to the series of operations including thecharge accumulation, the reset operation, and the charge transferaccording to existing techniques.

In Example 5, because the so-called overflowing electrons are sent tothe drive circuit via the charge drain electrode 26, it is possible tosuppress leakage into the charge accumulation section of an adjacentpixel, and it is possible to suppress the occurrence of blooming. Thismakes it possible to improve the imaging performance of the imagingelement.

Example 6

Example 6 is a modification of Examples 1 to 5, and relates to animaging element or the like including a plurality of charge accumulationelectrode segments of the present disclosure.

FIG. 28 is a schematic partial cross-sectional view of a portion of animaging element of Example 6. FIGS. 29 and 30 are equivalent circuitdiagrams of the imaging element of Example 6. FIG. 31 is a schematiclayout diagram of the first electrode and the charge accumulationelectrode included in the photoelectric conversion section including thecharge accumulation electrode, and the transistors included in thecontrol section of the imaging element of Example 6. FIGS. 32 and 33schematically illustrate a state of potentials at each part duringoperation of the imaging element of Example 6. FIG. 6C is an equivalentcircuit diagram for describing each part of the imaging element ofExample 6. In addition, FIG. 34 is a schematic layout diagram of thefirst electrode and the charge accumulation electrode included in thephotoelectric conversion section including the charge accumulationelectrode of the imaging element of Example 6. FIG. 35 is a schematictransparent perspective view of the first electrode, the chargeaccumulation electrode, the second electrode, and the contact holesection.

In Example 6, the charge accumulation electrode 24 includes a pluralityof charge accumulation electrode segments 24A, 24B, and 24C. The numberof the charge accumulation electrode segments only has to be two ormore, and is set to “3” in Example 6. In addition, in the imagingelement of Example 6, the potential of the first electrode 21 is higherthan the potential of the second electrode 22, i.e., for example, apositive potential is to be applied to the first electrode 21 and anegative potential is to be applied to the second electrode 22. Thus,during the charge transfer period, a potential to be applied to thecharge accumulation electrode segment 24A positioned closest to thefirst electrode 21 is higher than a potential to be applied to thecharge accumulation electrode segment 24C positioned farthest from thefirst electrode 21. By imparting a potential gradient to the chargeaccumulation electrode 24 in such a manner, the electrons remaining inthe region of the inorganic semiconductor material layer 23B or the likeopposed to the charge accumulation electrode 24 are read out to thefirst electrode 21, and further to the first floating diffusion layerFD₁ with higher reliability. That is, the electric charge accumulated inthe inorganic semiconductor material layer 23B or the like is read outto the control section.

In the example illustrated in FIG. 32, during the charge transferperiod, the electrons remaining in the region of the inorganicsemiconductor material layer 23B or the like are read out to the firstfloating diffusion layer FD₁ all at once by satisfying: the potential ofthe charge accumulation electrode segment 24C<the potential of thecharge accumulation electrode segment 24B<the potential of the chargeaccumulation electrode segment 24A. Meanwhile, in the exampleillustrated in FIG. 33, during the charge transfer period, the potentialof the charge accumulation electrode segment 24C, the potential of thecharge accumulation electrode segment 24B, and the potential of thecharge accumulation electrode segment 24A are changed gradually (i.e.,changed stepwise or in a slope-like manner). The electrons remaining ina region of the inorganic semiconductor material layer 23B or the likeopposed to the charge accumulation electrode segment 24C are therebymoved to a region of the inorganic semiconductor material layer 23B orthe like opposed to the charge accumulation electrode segment 24B, andsubsequently, the electrons remaining in the region of the inorganicsemiconductor material layer 23B or the like opposed to the chargeaccumulation electrode segment 24B are moved to a region of theinorganic semiconductor material layer 23B or the like opposed to thecharge accumulation electrode segment 24A. Subsequently, the electronsremaining in the region of the inorganic semiconductor material layer23B or the like opposed to the charge accumulation electrode segment 24Aare read out to the first floating diffusion layer FD₁ with reliability.

FIG. 36 is a schematic layout diagram of the first electrode and thecharge accumulation electrode, and the transistors included in thecontrol section that are included in a modification example of theimaging element of Example 6. As illustrated, the other source/drainregion 51B of the reset transistor TR1 _(rst) may be grounded, insteadof being coupled to the power supply V_(DD).

Example 7

Example 7 is a modification of Examples 1 to 6, and relates to animaging element or the like including the charge movement controlelectrode of the present disclosure, specifically, an imaging element orthe like including the lower charge movement control electrode (lowerside/charge movement control electrode) of the present disclosure. FIG.37 is a schematic partial cross-sectional view of a portion of animaging element of Example 7. FIG. 38 is a schematic layout diagram ofthe first electrode, the charge accumulation electrode and the like, andthe transistors included in the control section that are included in theimaging element of Example 7. FIGS. 39 and 40 are schematic layoutdiagrams of the first electrode, the charge accumulation electrode, andthe lower charge movement control electrode included in thephotoelectric conversion section including the charge accumulationelectrode of the imaging element of Example 7.

In the imaging element of Example 7, a lower charge movement controlelectrode 27 is formed in a region opposed to a region (region-A of thephotoelectric conversion layer) 23 _(A) of a photoelectric conversionstack 23 positioned between adjacent imaging elements, with theinsulating layer 82 interposed therebetween. In other words, the lowercharge movement control electrode 27 is formed below a portion 82 _(A)of the insulating layer 82 (region-A of the insulating layer 82) in aregion (region-a) sandwiched between a charge accumulation electrode 24and a charge accumulation electrode 24 that are included in respectiveadjacent imaging elements. The lower charge movement control electrode27 is provided at a distance from the charge accumulation electrodes 24.Or in other words, the lower charge movement control electrode 27surrounds the charge accumulation electrodes 24 and is provided at adistance from the charge accumulation electrodes 24, and the lowercharge movement control electrode 27 is disposed to be opposed to theregion-A (23 _(A)) of the photoelectric conversion layer with theinsulating layer 82 interposed therebetween. The lower charge movementcontrol electrode 27 is shared by the imaging elements. In addition, thelower charge movement control electrode 27 is also coupled to the drivecircuit. Specifically, the lower charge movement control electrode 27 iscoupled to the vertical drive circuit 112 included in the drive circuit,via a connection hole 27A, a pad section 27B, and a wiring line V_(OB)provided in the interlayer insulating layer 81. The lower chargemovement control electrode 27 may be formed at the same level as thefirst electrode 21 or the charge accumulation electrode 24, or may beformed at a different level (specifically, a level below the firstelectrode 21 or the charge accumulation electrode 24). In the formercase, it is possible to shorten the distance between the charge movementcontrol electrode 27 and the photoelectric conversion layer 23A, andthis makes it easy to control the potential. In contrast, in the lattercase, it is possible to shorten the distance between the charge movementcontrol electrode 27 and the charge accumulation electrode 24, and thisis advantageous in achieving miniaturization.

In the imaging element of Example 7, when light enters the photoelectricconversion layer 23A to generate photoelectric conversion in thephotoelectric conversion layer 23A, the absolute value of the potentialapplied to the portion of the photoelectric conversion layer 23A opposedto the charge accumulation electrode 24 is larger than the absolutevalue of the potential applied to the region-A of the photoelectricconversion layer 23A, and therefore, electric charge generated by thephotoelectric conversion is strongly attracted to the portion of theinorganic semiconductor material layer 23B opposed to the chargeaccumulation electrode 24. As a result, it is possible to hinder theelectric charge generated by the photoelectric conversion from flowinginto an adjacent imaging element. Therefore, no quality degradationoccurs in a captured picture (image). In addition, owing to the lowercharge movement control electrode 27 formed in a region opposed to theregion-A of the photoelectric conversion layer 23A with the insulatinglayer interposed therebetween, it is possible to control an electricfield or potential in the region-A of the photoelectric conversion layer23A positioned above the lower charge movement control electrode 27. Asa result, the lower charge movement control electrode 27 makes itpossible to hinder the electric charge generated by the photoelectricconversion from flowing into the adjacent imaging element. Therefore, noquality degradation occurs in a captured picture (image).

In the examples illustrated in FIGS. 39 and 40, the lower chargemovement control electrode 27 is formed below the portion 82 _(A) of theinsulating layer 82 in the region (region-a) sandwiched between thecharge accumulation electrode 24 and the charge accumulation electrode24. Meanwhile, in the examples illustrated in FIGS. 41, 42A and 42B, thelower charge movement control electrode 27 is formed below a portion ofthe insulating layer 82 in a region surrounded by four chargeaccumulation electrodes 24. It is to be noted that the examplesillustrated in FIGS. 41, 42A, and 42B are also the solid-state imagingdevices of the first and second configurations. In four imagingelements, one common first electrode 21 is provided to correspond to thefour charge accumulation electrodes 24.

In the example illustrated in FIG. 42B, in the four imaging elements,the one common first electrode 21 is provided to correspond to the fourcharge accumulation electrodes 24, and the lower charge movement controlelectrode 27 is formed below a portion of the insulating layer 82 in theregion surrounded by the four charge accumulation electrodes 24.Further, the charge drain electrode 26 is formed below the portion ofthe insulating layer 82 in the region surrounded by the four chargeaccumulation electrodes 24. As described above, the charge drainelectrode 26 is usable as a floating diffusion or overflow drain of thephotoelectric conversion section, for example.

Example 8

Example 8 is a modification of Example 7, and relates to an imagingelement or the like including the upper charge movement controlelectrode (upper side/charge movement control electrode) of the presentdisclosure. FIG. 43 is a partial schematic cross-sectional view of animaging element of Example 8 (two imaging elements arranged side byside). FIGS. 44 and 45 are partial schematic plan views of the imagingelement of Example 8 (2×2 imaging elements arranged side by side). Inthe imaging element of Example 8, an upper charge movement controlelectrode 28 is formed, instead of the second electrode 22, on a region23 _(A) of the photoelectric conversion stack 23 positioned betweenadjacent imaging elements. The upper charge movement control electrode28 is provided at a distance from the second electrode 22. In otherwords, the second electrode 22 is provided for each imaging element, andthe upper charge movement control electrode 28 surrounds at least aportion of the second electrode 22 and is provided, at a distance fromthe second electrode 22, on the region-A of the photoelectric conversionstack 23. The upper charge movement control electrode 28 is formed atthe same level as the second electrode 22.

It is to be noted that, in the example illustrated in FIG. 44, in oneimaging element, one charge accumulation electrode 24 is provided tocorrespond to one first electrode 21. Meanwhile, in a modificationexample illustrated in FIG. 45, in two imaging elements, one commonfirst electrode 21 is provided to correspond to the two chargeaccumulation electrodes 24. The partial schematic cross-sectional viewof the imaging element of Example 8 (two imaging elements arranged sideby side) illustrated in FIG. 43 corresponds to FIG. 45.

In addition, FIG. 46A is a partial schematic cross-sectional view of theimaging element of Example 8 (two imaging elements arranged side byside). As illustrated, the second electrode 22 may be divided into aplurality of ones, and different potentials may be applied to thedivided individual second electrodes 22. Further, as illustrated in FIG.46B, the upper charge movement control electrode 28 may be providedbetween the second electrode 22 and the second electrode 22 thusdivided.

In Example 8, the second electrode 22 positioned on the light incidentside is shared by the imaging elements arranged in the lateral directionon the sheet of FIG. 44, and shared by a pair of imaging elementsarranged in the up-and-down direction on the sheet of FIG. 44. Inaddition, the upper charge movement control electrode 28 is also sharedby the imaging elements arranged in the lateral direction on the sheetof FIG. 44, and shared by a pair of imaging elements arranged in theup-and-down direction on the sheet of FIG. 44. The second electrode 22and the upper charge movement control electrode 28 are obtainable byforming a material layer to configure the second electrode 22 and theupper charge movement control electrode 28 on the photoelectricconversion stack 23 and thereafter patterning the material layer. Thesecond electrode 22 and the upper charge movement control electrode 28are coupled to respective wiring lines (not illustrated) independentlyof each other, and these wiring lines are coupled to the drive circuit.The wiring line coupled to the second electrode 22 is shared by aplurality of imaging elements. The wiring line coupled to the uppercharge movement control electrode 28 is also shared by a plurality ofimaging elements.

In the imaging element of Example 8, during a charge accumulationperiod, from the drive circuit, the potential V₂₁ is applied to thesecond electrode 22, the potential V₄₁ is applied to the upper chargemovement control electrode 28, and electric charge is accumulated in thephotoelectric conversion stack 23. During a charge transfer period, fromthe drive circuit, the potential V₂₂ is applied to the second electrode22, the potential V₄₂ is applied to the upper charge movement controlelectrode 28, and the electric charge accumulated in the photoelectricconversion stack 23 is read out to the control section via the firstelectrode 21. Here, the potential of the first electrode 21 is higherthan the potential of the second electrode 22, and therefore,

V₂₁ ≥ V₄₁  and  V₂₂ ≥ V₄₂

hold true.

As described above, in the imaging element of Example 8, the chargemovement control electrode is formed, instead of the second electrode,on the region of the photoelectric conversion layer positioned betweenadjacent imaging elements. The charge movement control electrode thusmakes it possible to hinder the electric charge generated byphotoelectric conversion from flowing into the adjacent imaging element,and therefore no quality degradation occurs in a captured picture(image).

FIG. 47A is a partial schematic cross-sectional view of a modificationexample of the imaging element of Example 8 (two imaging elementsarranged side by side), and FIGS. 48A and 48B are partial schematic planviews thereof. In this modification example, the second electrode 22 isprovided for each imaging element, the upper charge movement controlelectrode 28 surrounds at least a portion of the second electrode 22 andis provided at a distance from the second electrode 22, and a portion ofthe charge accumulation electrode 24 is present below the upper chargemovement control electrode 28. The second electrode 22 is provided,above the charge accumulation electrode 24, in a size smaller than thatof the charge accumulation electrode 24.

FIG. 47B is a partial schematic cross-sectional view of a modificationexample of the imaging element of Example 8 (two imaging elementsarranged side by side), and FIGS. 49A and 49B are partial schematic planviews thereof. In this modification example, the second electrode 22 isprovided for each imaging element, the upper charge movement controlelectrode 28 surrounds at least a portion of the second electrode 22 andis provided at a distance from the second electrode 22, a portion of thecharge accumulation electrode 24 is present below the upper chargemovement control electrode 28, and furthermore, the lower chargemovement control electrode (lower side/charge movement controlelectrode) 27 is provided below the upper charge movement controlelectrode (upper side/charge movement control electrode) 28. The size ofthe second electrode 22 is smaller than that in the modification exampleillustrated in FIG. 47A. That is, the region of the second electrode 22opposed to the upper charge movement control electrode 28 is positionedcloser to the first electrode 21 than the region of the second electrode22 opposed to the upper charge movement control electrode 28 in themodification example illustrated in FIG. 47A. The charge accumulationelectrode 24 is surrounded by the lower charge movement controlelectrode 27.

Example 9

Example 9 relates to the solid-state imaging devices of the first andsecond configurations.

A solid-state imaging device of Example 9 includes a photoelectricconversion section including the first electrode 21, the inorganicsemiconductor material layer 23B, the photoelectric conversion layer23A, and the second electrode 22 that are stacked, in which thephotoelectric conversion section further includes a plurality of imagingelements each including the charge accumulation electrode 24 disposed ata distance from the first electrode 21 and disposed to be opposed to theinorganic semiconductor material layer 23B with the insulating layer 82interposed therebetween, the plurality of imaging elements constitute animaging element block, and the first electrode 21 is shared by theplurality of imaging elements constituting the imaging element block.

Alternatively, the solid-state imaging device of Example 9 includes aplurality of imaging elements described in Examples 1 to 8.

In Example 9, one floating diffusion layer is provided for the pluralityof imaging elements. Then, appropriately controlling the timing of thecharge transfer period makes it possible for the plurality of imagingelements to share the one floating diffusion layer. Then, in this case,it is possible for the plurality of imaging elements to share onecontact hole section.

It is to be noted that the solid-state imaging device of Example 9 has aconfiguration and a structure similar to those of the solid-stateimaging devices described in Examples 1 to 8, except that the firstelectrode 21 is shared by the plurality of imaging elements constitutingthe imaging element block.

The states of arrangement of the first electrode 21 and the chargeaccumulation electrode 24 in the solid-state imaging device of Example 9are schematically illustrated in FIG. 50 (Example 9), FIG. 51 (a firstmodification example of Example 9), FIG. 52 (a second modificationexample of Example 9), FIG. 53 (a third modification example of Example9), and FIG. 54 (a fourth modification example of Example 9). FIGS. 50,51, 54, and 55 illustrate sixteen imaging elements, and FIGS. 52 and 53illustrate twelve imaging elements. Then, the imaging element block isconstituted of two imaging elements. The imaging element block isindicated by enclosing with dotted lines. Subscripts attached to thefirst electrodes 21 and the charge accumulation electrodes 24 are fordistinguishing individual first electrodes 21 and individual chargeaccumulation electrodes 24. The same applies also to the followingdescription. In addition, one on-chip microlens (not illustrated inFIGS. 50 to 57) is disposed above one imaging element. Then, in oneimaging element block, two charge accumulation electrodes 24 aredisposed with the first electrode 21 therebetween (see FIGS. 50 and 51).Alternatively, one first electrode 21 is disposed to be opposed to twocharge accumulation electrodes 24 arranged side by side (see FIGS. 54and 55). That is, the first electrode is disposed to be adjacent to thecharge accumulation electrode of each imaging element. Alternatively,the first electrode is disposed to be adjacent to some of the chargeaccumulation electrodes of the plurality of imaging elements and notdisposed to be adjacent to the rest of the charge accumulationelectrodes of the plurality of imaging elements (see FIGS. 52 and 53),in which case the movement of electric charge from the rest of theplurality of imaging elements to the first electrode is a movement viasome of the plurality of imaging elements. To ensure movement ofelectric charge from each imaging element to the first electrode, it ispreferred that a distance A between a charge accumulation electrodeincluded in an imaging element and a charge accumulation electrodeincluded in an imaging element be longer than a distance B between thefirst electrode and the charge accumulation electrode in an imagingelement adjacent to the first electrode. In addition, it is preferredthat the value of the distance A be larger for the imaging elementpositioned farther from the first electrode. In addition, in theexamples illustrated in FIGS. 51, 53, and 55, the charge movementcontrol electrode 27 is disposed between a plurality of imaging elementsconstituting the imaging element block. By disposing the charge movementcontrol electrode 27, it is possible to suppress, with reliability, themovement of electric charge in the imaging element blocks positionedwith the charge movement control electrode 27 therebetween. It is to benoted that it is sufficient that V₃₁>V₁₇ holds true, where V₁₇ denotes apotential to be applied to the charge movement control electrode 27.

The charge movement control electrode 27 may be formed at the same levelas the first electrode 21 or the charge accumulation electrode 24, ormay be formed at a different level (specifically, a level below thefirst electrode 21 or the charge accumulation electrode 24). In theformer case, it is possible to shorten the distance between the chargemovement control electrode 27 and the photoelectric conversion layer,and this makes it easy to control the potential. In contrast, in thelatter case, it is possible to shorten the distance between the chargemovement control electrode 27 and the charge accumulation electrode 24,and this is advantageous in achieving miniaturization.

In the following, description is given of an operation of the imagingelement block including a first electrode 21 ₂ and two chargeaccumulation electrodes 24 ₂₁ and 24 ₂₂.

During a charge accumulation period, from the drive circuit, thepotential V₁₁ is applied to the first electrode 21 ₂ and the potentialV₃₁ is applied to the charge accumulation electrodes 24 ₂₁ and 24 ₂₂.Light having entered the photoelectric conversion layer 23A generatesphotoelectric conversion in the photoelectric conversion layer 23A.Holes generated by the photoelectric conversion are sent from the secondelectrode 22 to the drive circuit via the wiring line V_(OU). Meanwhile,the potential V₁₁ of the first electrode 21 ₂ is higher than thepotential V₂₁ of the second electrode 22, i.e., for example, a positivepotential is to be applied to the first electrode 21 ₂ and a negativepotential is to be applied to the second electrode 22. Thus, V₃₁≥V₁₁holds true, and preferably, V₃₁>V₁₁ holds true. This causes electronsgenerated by the photoelectric conversion to be attracted to the chargeaccumulation electrodes 24 ₂₁ and 24 ₂₂, and to remain in regions of theinorganic semiconductor material layer 23B or the like opposed to thecharge accumulation electrodes 24 ₂₁ and 24 ₂₂. That is, electric chargeis accumulated in the inorganic semiconductor material layer 23B or thelike. Because V₃₁≥V₁₁ holds true, the electrons generated inside of thephotoelectric conversion layer 23A would not move toward the firstelectrode 21 ₂. With the passage of time of photoelectric conversion,the potentials in regions of the inorganic semiconductor material layer23B or the like opposed to the charge accumulation electrodes 24 ₂₁ and24 ₂₂ have more negative values.

A reset operation is performed later in the charge accumulation period.This resets the potential of the first floating diffusion layer, and thepotential of the first floating diffusion layer shifts to the potentialV_(DD) of the power supply.

After completion of the reset operation, the electric charge is readout. That is, during a charge transfer period, from the drive circuit,the potential V₂₁ is applied to the first electrode 21 ₂, a potentialV_(32-A) is applied to the charge accumulation electrode 24 ₂₁, and apotential V_(32-B) is applied to the charge accumulation electrode 24₂₂. Here, V_(32-A)<V₂₁<V_(32-B) holds true. This causes the electronsremaining in the region of the inorganic semiconductor material layer23B or the like opposed to the charge accumulation electrode 24 ₂₁ to beread out to the first electrode 21 ₂, and further to the first floatingdiffusion layer. That is, the electric charge accumulated in the regionof the inorganic semiconductor material layer 23B or the like opposed tothe charge accumulation electrode 24 ₂₁ is read out to the controlsection. Once the reading has been completed, V_(32-B)≤V_(32-A)<V₂₁holds true. It is to be noted that, in the examples illustrated in FIGS.54 and 55, V_(32-B)<V₂₁<V_(32-A) may hold true. This causes theelectrons remaining in the region of the inorganic semiconductormaterial layer 23B or the like opposed to the charge accumulationelectrode 24 ₂₂ to be read out to the first electrode 21 ₂, and furtherto the first floating diffusion layer. In addition, in the examplesillustrated in FIGS. 52 and 53, the electrons remaining in the region ofthe inorganic semiconductor material layer 23B or the like opposed tothe charge accumulation electrode 24 ₂₂ may be read out to the firstfloating diffusion layer via a first electrode 213 to which the chargeaccumulation electrode 24 ₂₂ is adjacent. In this way, the electriccharge accumulated in the region of the inorganic semiconductor materiallayer 23B or the like opposed to the charge accumulation electrode 24 ₂₂is read out to the control section. It is to be noted that, once thereading of the electric charge accumulated in the region of theinorganic semiconductor material layer 23B or the like opposed to thecharge accumulation electrode 24 ₂₁ to the control section has beencompleted, the potential of the first floating diffusion layer may bereset.

FIG. 58A illustrates an example of reading and driving in the imagingelement block of Example 9.

[Step-A]

Inputting auto zero signal to comparator

[Step-B]

Reset operation of one shared floating diffusion layer

[Step-C]

P-phase reading in imaging element corresponding to charge accumulationelectrode 24 ₂₁ and movement of electric charge to first electrode 21 ₂

[Step-D]

D-phase reading in imaging element corresponding to charge accumulationelectrode 24 ₂₁ and movement of electric charge to first electrode 21 ₂

[Step-E]

Reset operation of one shared floating diffusion layer

[Step-F]

Inputting auto zero signal to comparator

[Step-G]

P-phase reading in imaging element corresponding to charge accumulationelectrode 24 ₂₂ and movement of electric charge to first electrode 21 ₂

[Step-H]

D-phase reading in imaging element corresponding to charge accumulationelectrode 24 ₂₂ and movement of electric charge to first electrode 21 ₂

In accordance with the above flow, signals from two imaging elementscorresponding to the charge accumulation electrode 24 ₂₁ and the chargeaccumulation electrode 24 ₂₂ are read out. On the basis of a correlateddouble sampling (CDS) process, a difference between the P-phase readingin [Step-C] and the D-phase reading in [Step-D] is a signal from theimaging element corresponding to the charge accumulation electrode 24₂₁, and a difference between the P-phase reading in [Step-G] and theD-phase reading in [Step-H] is a signal from the imaging elementcorresponding to the charge accumulation electrode 24 ₂₂.

It is to be noted that the operation of [Step-E] may be omitted (seeFIG. 58B). In addition, the operation of [Step-F] may be omitted, and inthis case, it is possible to further omit [Step-G] (see FIG. 58C); then,a difference between the P-phase reading in [Step-C] and the D-phasereading in [Step-D] is a signal from the imaging element correspondingto the charge accumulation electrode 24 ₂₁, and a difference between theD-phase reading in [Step-D] and the D-phase reading in [Step-H] is asignal from the imaging element corresponding to the charge accumulationelectrode 24 ₂₂.

The states of arrangement of the first electrode 21 and the chargeaccumulation electrode 24 in modification examples are schematicallyillustrated in FIG. 56 (a sixth modification example of Example 9) andFIG. 57 (a seventh modification example of Example 9). In thesemodification examples, four imaging elements constitute an imagingelement block. Operations of these solid-state imaging devices may besubstantially similar to the operations of the solid-state imagingdevices illustrated in FIGS. 50 to 55.

In the solid-state imaging device of Example 9, the first electrode isshared by a plurality of imaging elements constituting the imagingelement block. It is thus possible to simplify and miniaturize theconfiguration and structure in the pixel region in which a plurality ofimaging elements are arranged. It is to be noted that a plurality ofimaging elements provided for one floating diffusion layer may beconstituted of a plurality of imaging elements of the first type, or maybe constituted of at least one imaging element of the first type and oneor two or more imaging elements of the second type.

Example 10

Example 10 is a modification of Example 9. The states of arrangement ofthe first electrode 21 and the charge accumulation electrode 24 thereofare schematically illustrated in FIGS. 59, 60, 61, and 62. In thesolid-state imaging device of Example 10, two imaging elementsconstitute an imaging element block. In addition, one on-chip microlens14 is disposed above the imaging element block. It is to be noted that,in the examples illustrated in FIGS. 60 and 62, the charge movementcontrol electrode 27 is disposed between the plurality of imagingelements constituting the imaging element block.

For example, photoelectric conversion layers corresponding to chargeaccumulation electrodes 24 ₁₁, 24 ₂₁, 24 ₃₁, and 24 ₄₁ constitutingimaging element blocks have high sensitivity to incident lightdiagonally from the upper right in the drawing. In addition,photoelectric conversion layers corresponding to charge accumulationelectrodes 24 ₁₂, 24 ₂₂, 24 ₃₂, and 24 ₄₂ constituting imaging elementblocks have high sensitivity to incident light diagonally from the upperleft in the drawing. Therefore, for example, combining an imagingelement including the charge accumulation electrode 24 ₁₁ and an imagingelement including the charge accumulation electrode 24 ₁₂ makes itpossible to acquire an image plane phase difference signal. In addition,by adding up a signal from the imaging element including the chargeaccumulation electrode 24 ₁₁ and a signal from the imaging elementincluding the charge accumulation electrode 24 ₁₂, it is possible toconfigure one imaging element by a combination with these imagingelements. In the example illustrated in FIG. 59, a first electrode 21 ₁is disposed between the charge accumulation electrode 24 ₁₁ and thecharge accumulation electrode 24 ₁₂; however, by disposing one firstelectrode 21 ₁ to be opposed to two charge accumulation electrodes 24 ₁₁and 24 ₁₂ arranged side by side as in the example illustrated in FIG.61, it is possible to achieve further improvement in sensitivity.

While the description has been given above of the present disclosure onthe basis of preferred examples, the present disclosure is not limitedto these examples. The structures and configurations, manufacturingconditions, manufacturing methods, and materials used of the imagingelements, the stacked imaging elements, and the solid-state imagingdevices described in the examples are merely illustrative, and may bemodified as appropriate. The imaging elements of the examples may becombined as appropriate. The configuration and structure of the imagingelement of the present disclosure are applicable to light emittingelements, e.g., organic EL elements, or channel formation regions ofthin-film transistors.

Depending on the case, the floating diffusion layers FD₁, FD₂, FD₃, 51C,45C, and 46C may also be shared, as has been described.

In addition, FIG. 63 illustrates a modification example of the imagingelement and the stacked imaging element described in Example 1. Asillustrated, for example, a configuration may be adopted in which lightenters from side of the second electrode 22 and a light-blocking layer15 is formed on the light incident side near the second electrode 22. Itis to be noted that various wiring lines provided closer to the lightincident side than the photoelectric conversion layer may also serve asa light-blocking layer.

It is to be noted that, in the example illustrated in FIG. 63, thelight-blocking layer 15 is formed above the second electrode 22, i.e.,the light-blocking layer 15 is formed on the light incident side nearthe second electrode 22 and above the first electrode 21; however, asillustrated in FIG. 64, the light-blocking layer 15 may be disposed on asurface of the second electrode 22 on the light incident side. Inaddition, as illustrated in FIG. 65, the second electrode 22 may beprovided with the light-blocking layer 15, depending on the case.

Alternatively, a structure may be adopted in which light enters from theside of the second electrode 22 and no light enters the first electrode21. Specifically, as illustrated in FIG. 63, the light-blocking layer 15is formed on the light incident side near the second electrode 22 andabove the first electrode 21. Alternatively, a structure may be adoptedin which, as illustrated in FIG. 67, the on-chip microlens 14 isprovided above the charge accumulation electrode 24 and the secondelectrode 22, and light entering the on-chip microlens 14 is condensedonto the charge accumulation electrode 24 and does not reach the firstelectrode 21. It is to be noted that, as described in Example 4, in thecase where the transfer control electrode 25 is provided, a mode may beadopted in which light enters neither of the first electrode 21 and thetransfer control electrode 25. Specifically, a structure may be adoptedin which, as illustrated in FIG. 66, the light-blocking layer 15 isformed above the first electrode 21 and the transfer control electrode25. Alternatively, a structure may be adopted in which the lightentering the on-chip microlens 14 does not reach the first electrode 21,or reaches neither of the first electrode 21 and the transfer controlelectrode 25.

By employing these configurations and structures, or by providing thelight-blocking layer 15 to allow light to enter only a portion of thephotoelectric conversion section positioned above the chargeaccumulation electrode 24, or by designing the on-chip microlens 14, theportion of the photoelectric conversion section positioned above thefirst electrode 21 (or above the first electrode 21 and the transfercontrol electrode 25) becomes unable to contribute to photoelectricconversion, and it is thus possible to reset all the pixels all at oncewith higher reliability, and to achieve the global shutter function moreeasily. Thus, in a method of driving a solid-state imaging deviceincluding a plurality of imaging elements having these configurationsand structures, the following steps are repeated:

draining, in all of the imaging elements, electric charge in the firstelectrodes 21 out of the system all at once while accumulating electriccharge in the inorganic semiconductor material layers 23B or the like,and thereafter transferring, in all of the imaging elements, theelectric charge accumulated in the inorganic semiconductor materiallayers 23B or the like to the first electrodes 21 all at once, and aftercompletion of the transfer, reading out the electric charge transferredto the first electrodes 21 in the respective imaging elementssequentially.

In such a method of driving the solid-state imaging device, each imagingelement has a structure in which light having entered from the side ofthe second electrode does not enter the first electrode and, in all ofthe imaging elements, the electric charge in the first electrodes isdrained out of the system all at once while accumulating electric chargein the inorganic semiconductor material layers or the like. This makesit possible to perform resetting of the first electrodes in all of theimaging elements simultaneously with reliability. Thereafter, in all ofthe imaging elements, the electric charge accumulated in the inorganicsemiconductor material layers or the like is transferred all at once tothe first electrodes, and after completion of the transfer, the electriccharge transferred to the first electrodes is read out in the imagingelements sequentially. It is thus possible to easily achieve theso-called global shutter function.

In a case where one inorganic semiconductor material layer 23B shared bya plurality of imaging elements is formed, it is desirable that an endpart of the inorganic semiconductor material layer 23B be covered withat least the photoelectric conversion layer 23A, from the viewpoint ofprotection of the end part of the inorganic semiconductor material layer23B. For the structure of the imaging element in such a case, astructure as illustrated at the right end of the schematiccross-sectional view of the inorganic semiconductor material layer 23Billustrated in FIG. 1 is sufficient.

In addition, as a modification example of Example 4, as illustrated inFIG. 67, a plurality of transfer control electrodes may be provided froma position closest to the first electrode 21 toward the chargeaccumulation electrode 24. It is to be noted that FIG. 67 illustrates anexample in which two transfer control electrodes 25A and 25B areprovided. Then, a structure may be adopted in which the on-chipmicrolens 14 is provided above the charge accumulation electrode 24 andthe second electrode 22, so that light entering the on-chip microlens 14is condensed onto the charge accumulation electrode 24 and reaches noneof the first electrode 21 and the transfer control electrodes 25A and25B.

The first electrode 21 may be configured to extend in the opening 84provided in the insulating layer 82 and to be coupled to the inorganicsemiconductor material layer 23B.

In addition, in Examples, description has been given with reference to,as an example, a case of application to a CMOS type solid-state imagingdevice in which unit pixels are arranged in matrix for sensing signalcharge responsive to the amount of incident light as a physicalquantity; however, the application to the CMOS type solid-state imagingdevice is not limitative, and application to a CCD type solid-stateimaging device is also possible. In the latter case, the signal chargeis transferred in the vertical direction by a vertical transfer registerof a CCD type structure, transferred in the horizontal direction by ahorizontal transfer register, and then amplified to thereby cause apixel signal (image signal) to be outputted. In addition, possibleapplications are not limited to column-system solid-state imagingdevices in general in which pixels are formed in a two-dimensionalmatrix pattern and a column signal processing circuit is disposed foreach pixel column. Further, depending on the case, the selectiontransistor may be omitted.

Further, the imaging element and the stacked imaging element of thepresent disclosure are applicable not only to a solid-state imagingdevice that senses the distribution of incident amount of visible lightto capture an image of the distribution, but also to a solid-stateimaging device that captures an image of the distribution of incidentamount of infrared rays, X-rays, particles, or the like. In addition, ina broad sense, the imaging element and the stacked imaging element ofthe present disclosure are generally applicable to a solid-state imagingdevice (physical quantity distribution sensing device) that senses thedistribution of other physical quantities, including pressure andcapacitance, to capture an image of the distribution, such as afingerprint detection sensor.

Further, possible applications are not limited to a solid-state imagingdevice that sequentially scans unit pixels in an imaging region row byrow and reads out pixel signals from the unit pixels. Application to anX-Y address type solid-state imaging device is also possible thatselects any pixel on a per-pixel basis and reads out a pixel signal fromthe selected pixel on a per-pixel basis. The solid-state imaging devicemay be formed in a one-chip form or may be in a modular form with animaging function in which the imaging region and the drive circuit orthe optical system are packaged together.

In addition, possible applications are not limited to a solid-stateimaging device, and application to an imaging device is also possible.Here, the imaging device refers to an electronic apparatus having animaging function, examples of which include camera systems such as adigital still camera or a video camera, mobile phones, etc. In somecases, the imaging device may also be an imaging device in a modularform to be mounted on an electronic apparatus, i.e., a camera module.

FIG. 69 illustrates, as a conceptual diagram, an example of using asolid-state imaging device 201 including the imaging element and thestacked imaging element of the present disclosure in an electronicapparatus (camera) 200. The electronic apparatus 200 includes thesolid-state imaging device 201, an optical lens 210, a shutter device211, a drive circuit 212, and a signal processing circuit 213. Theoptical lens 210 focuses image light (incident light) from a subject toform an image on an imaging plane of the solid-state imaging device 201.This causes signal charge to be accumulated in the solid-state imagingdevice 201 for a predetermined period of time. The shutter device 211controls a period during which the solid-state imaging device 201 is tobe irradiated with light and a period during which the light is to beblocked. The drive circuit 212 supplies drive signals for controlling atransfer operation, etc. of the solid-state imaging device 201 and ashutter operation of the shutter device 211. Signal transfer in thesolid-state imaging device 201 is performed in accordance with the drivesignals (timing signals) supplied from the drive circuit 212. The signalprocessing circuit 213 performs various kinds of signal processing. Animage signal having undergone the signal processing is stored in astorage medium such as a memory, or is outputted to a monitor. In suchan electronic apparatus 200, the solid-state imaging device 201 is ableto achieve miniaturization of pixel size and improvement in transferefficiency, thus making it possible to provide the electronic apparatus200 with improved pixel characteristics. Examples of the electronicapparatus 200 to which the solid-state imaging device 201 is applicableare not limited to a camera, but includes a digital still camera, acamera module for a mobile apparatus such as a mobile phone, and otherimaging devices.

The technology according to the present disclosure (the presenttechnology) is applicable to various products. For example, thetechnology according to the present disclosure may be implemented as adevice to be mounted on any type of mobile body such as an automobile,an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle,a personal mobility, an airplane, a drone, a vessel, or a robot.

FIG. 77 is a block diagram depicting an example of schematicconfiguration of a vehicle control system as an example of a mobile bodycontrol system to which the technology according to an embodiment of thepresent disclosure can be applied.

The vehicle control system 12000 includes a plurality of electroniccontrol units connected to each other via a communication network 12001.In the example depicted in FIG. 77, the vehicle control system 12000includes a driving system control unit 12010, a body system control unit12020, an outside-vehicle information detecting unit 12030, anin-vehicle information detecting unit 12040, and an integrated controlunit 12050. In addition, a microcomputer 12051, a sound/image outputsection 12052, and a vehicle-mounted network interface (I/F) 12053 areillustrated as a functional configuration of the integrated control unit12050.

The driving system control unit 12010 controls the operation of devicesrelated to the driving system of the vehicle in accordance with variouskinds of programs. For example, the driving system control unit 12010functions as a control device for a driving force generating device forgenerating the driving force of the vehicle, such as an internalcombustion engine, a driving motor, or the like, a driving forcetransmitting mechanism for transmitting the driving force to wheels, asteering mechanism for adjusting the steering angle of the vehicle, abraking device for generating the braking force of the vehicle, and thelike.

The body system control unit 12020 controls the operation of variouskinds of devices provided to a vehicle body in accordance with variouskinds of programs. For example, the body system control unit 12020functions as a control device for a keyless entry system, a smart keysystem, a power window device, or various kinds of lamps such as aheadlamp, a backup lamp, a brake lamp, a turn signal, a fog lamp, or thelike. In this case, radio waves transmitted from a mobile device as analternative to a key or signals of various kinds of switches can beinput to the body system control unit 12020. The body system controlunit 12020 receives these input radio waves or signals, and controls adoor lock device, the power window device, the lamps, or the like of thevehicle.

The outside-vehicle information detecting unit 12030 detects informationabout the outside of the vehicle including the vehicle control system12000. For example, the outside-vehicle information detecting unit 12030is connected with an imaging section 12031. The outside-vehicleinformation detecting unit 12030 makes the imaging section 12031 imagean image of the outside of the vehicle, and receives the imaged image.On the basis of the received image, the outside-vehicle informationdetecting unit 12030 may perform processing of detecting an object suchas a human, a vehicle, an obstacle, a sign, a character on a roadsurface, or the like, or processing of detecting a distance thereto.

The imaging section 12031 is an optical sensor that receives light, andwhich outputs an electric signal corresponding to a received lightamount of the light. The imaging section 12031 can output the electricsignal as an image, or can output the electric signal as informationabout a measured distance. In addition, the light received by theimaging section 12031 may be visible light, or may be invisible lightsuch as infrared rays or the like.

The in-vehicle information detecting unit 12040 detects informationabout the inside of the vehicle. The in-vehicle information detectingunit 12040 is, for example, connected with a driver state detectingsection 12041 that detects the state of a driver. The driver statedetecting section 12041, for example, includes a camera that images thedriver. On the basis of detection information input from the driverstate detecting section 12041, the in-vehicle information detecting unit12040 may calculate a degree of fatigue of the driver or a degree ofconcentration of the driver, or may determine whether the driver isdozing.

The microcomputer 12051 can calculate a control target value for thedriving force generating device, the steering mechanism, or the brakingdevice on the basis of the information about the inside or outside ofthe vehicle which information is obtained by the outside-vehicleinformation detecting unit 12030 or the in-vehicle information detectingunit 12040, and output a control command to the driving system controlunit 12010. For example, the microcomputer 12051 can perform cooperativecontrol intended to implement functions of an advanced driver assistancesystem (ADAS) which functions include collision avoidance or shockmitigation for the vehicle, following driving based on a followingdistance, vehicle speed maintaining driving, a warning of collision ofthe vehicle, a warning of deviation of the vehicle from a lane, or thelike.

In addition, the microcomputer 12051 can perform cooperative controlintended for automatic driving, which makes the vehicle to travelautonomously without depending on the operation of the driver, or thelike, by controlling the driving force generating device, the steeringmechanism, the braking device, or the like on the basis of theinformation about the outside or inside of the vehicle which informationis obtained by the outside-vehicle information detecting unit 12030 orthe in-vehicle information detecting unit 12040.

In addition, the microcomputer 12051 can output a control command to thebody system control unit 12020 on the basis of the information about theoutside of the vehicle which information is obtained by theoutside-vehicle information detecting unit 12030. For example, themicrocomputer 12051 can perform cooperative control intended to preventa glare by controlling the headlamp so as to change from a high beam toa low beam, for example, in accordance with the position of a precedingvehicle or an oncoming vehicle detected by the outside-vehicleinformation detecting unit 12030.

The sound/image output section 12052 transmits an output signal of atleast one of a sound and an image to an output device capable ofvisually or auditorily notifying information to an occupant of thevehicle or the outside of the vehicle. In the example of FIG. 77, anaudio speaker 12061, a display section 12062, and an instrument panel12063 are illustrated as the output device. The display section 12062may, for example, include at least one of an on-board display and ahead-up display.

FIG. 78 is a diagram depicting an example of the installation positionof the imaging section 12031.

In FIG. 78, a vehicle 12100 includes, as the imaging section 12031,imaging sections 12101, 12102, 12103, 12104, and 12105.

The imaging sections 12101, 12102, 12103, 12104, and 12105 are, forexample, disposed at positions on a front nose, sideview mirrors, a rearbumper, and a back door of the vehicle 12100 as well as a position on anupper portion of a windshield within the interior of the vehicle. Theimaging section 12101 provided to the front nose and the imaging section12105 provided to the upper portion of the windshield within theinterior of the vehicle obtain mainly an image of the front of thevehicle 12100. The imaging sections 12102 and 12103 provided to thesideview mirrors obtain mainly an image of the sides of the vehicle12100. The imaging section 12104 provided to the rear bumper or the backdoor obtains mainly an image of the rear of the vehicle 12100. Theimages of the front obtained by the imaging sections 12101 and 12105 areused mainly to detect a preceding vehicle, a pedestrian, an obstacle, asignal, a traffic sign, a lane, or the like.

Incidentally, FIG. 78 depicts an example of photographing ranges of theimaging sections 12101 to 12104. An imaging range 12111 represents theimaging range of the imaging section 12101 provided to the front nose.Imaging ranges 12112 and 12113 respectively represent the imaging rangesof the imaging sections 12102 and 12103 provided to the sideviewmirrors. An imaging range 12114 represents the imaging range of theimaging section 12104 provided to the rear bumper or the back door. Abird's-eye image of the vehicle 12100 as viewed from above is obtainedby superimposing image data imaged by the imaging sections 12101 to12104, for example.

At least one of the imaging sections 12101 to 12104 may have a functionof obtaining distance information. For example, at least one of theimaging sections 12101 to 12104 may be a stereo camera constituted of aplurality of imaging elements, or may be an imaging element havingpixels for phase difference detection.

For example, the microcomputer 12051 can determine a distance to eachthree-dimensional object within the imaging ranges 12111 to 12114 and atemporal change in the distance (relative speed with respect to thevehicle 12100) on the basis of the distance information obtained fromthe imaging sections 12101 to 12104, and thereby extract, as a precedingvehicle, a nearest three-dimensional object in particular that ispresent on a traveling path of the vehicle 12100 and which travels insubstantially the same direction as the vehicle 12100 at a predeterminedspeed (for example, equal to or more than 0 km/hour). Further, themicrocomputer 12051 can set a following distance to be maintained infront of a preceding vehicle in advance, and perform automatic brakecontrol (including following stop control), automatic accelerationcontrol (including following start control), or the like. It is thuspossible to perform cooperative control intended for automatic drivingthat makes the vehicle travel autonomously without depending on theoperation of the driver or the like.

For example, the microcomputer 12051 can classify three-dimensionalobject data on three-dimensional objects into three-dimensional objectdata of a two-wheeled vehicle, a standard-sized vehicle, a large-sizedvehicle, a pedestrian, a utility pole, and other three-dimensionalobjects on the basis of the distance information obtained from theimaging sections 12101 to 12104, extract the classifiedthree-dimensional object data, and use the extracted three-dimensionalobject data for automatic avoidance of an obstacle. For example, themicrocomputer 12051 identifies obstacles around the vehicle 12100 asobstacles that the driver of the vehicle 12100 can recognize visuallyand obstacles that are difficult for the driver of the vehicle 12100 torecognize visually. Then, the microcomputer 12051 determines a collisionrisk indicating a risk of collision with each obstacle. In a situationin which the collision risk is equal to or higher than a set value andthere is thus a possibility of collision, the microcomputer 12051outputs a warning to the driver via the audio speaker 12061 or thedisplay section 12062, and performs forced deceleration or avoidancesteering via the driving system control unit 12010. The microcomputer12051 can thereby assist in driving to avoid collision.

At least one of the imaging sections 12101 to 12104 may be an infraredcamera that detects infrared rays. The microcomputer 12051 can, forexample, recognize a pedestrian by determining whether or not there is apedestrian in imaged images of the imaging sections 12101 to 12104. Suchrecognition of a pedestrian is, for example, performed by a procedure ofextracting characteristic points in the imaged images of the imagingsections 12101 to 12104 as infrared cameras and a procedure ofdetermining whether or not it is the pedestrian by performing patternmatching processing on a series of characteristic points representingthe contour of the object. When the microcomputer 12051 determines thatthere is a pedestrian in the imaged images of the imaging sections 12101to 12104, and thus recognizes the pedestrian, the sound/image outputsection 12052 controls the display section 12062 so that a squarecontour line for emphasis is displayed so as to be superimposed on therecognized pedestrian. The sound/image output section 12052 may alsocontrol the display section 12062 so that an icon or the likerepresenting the pedestrian is displayed at a desired position.

In addition, for example, the technology according to the presentdisclosure may be applied to an endoscopic surgery system.

FIG. 79 is a view depicting an example of a schematic configuration ofan endoscopic surgery system to which the technology according to anembodiment of the present disclosure (present technology) can beapplied.

In FIG. 79, a state is illustrated in which a surgeon (medical doctor)11131 is using an endoscopic surgery system 11000 to perform surgery fora patient 11132 on a patient bed 11133. As depicted, the endoscopicsurgery system 11000 includes an endoscope 11100, other surgical tools11110 such as a pneumoperitoneum tube 11111 and an energy device 11112,a supporting arm apparatus 11120 which supports the endoscope 11100thereon, and a cart 11200 on which various apparatus for endoscopicsurgery are mounted.

The endoscope 11100 includes a lens barrel 11101 having a region of apredetermined length from a distal end thereof to be inserted into abody cavity of the patient 11132, and a camera head 11102 connected to aproximal end of the lens barrel 11101. In the example depicted, theendoscope 11100 is depicted which includes as a rigid endoscope havingthe lens barrel 11101 of the hard type. However, the endoscope 11100 mayotherwise be included as a flexible endoscope having the lens barrel11101 of the flexible type.

The lens barrel 11101 has, at a distal end thereof, an opening in whichan objective lens is fitted. A light source apparatus 11203 is connectedto the endoscope 11100 such that light generated by the light sourceapparatus 11203 is introduced to a distal end of the lens barrel 11101by a light guide extending in the inside of the lens barrel 11101 and isirradiated toward an observation target in a body cavity of the patient11132 through the objective lens. It is to be noted that the endoscope11100 may be a forward-viewing endoscope or may be an oblique-viewingendoscope or a side-viewing endoscope.

An optical system and an image pickup element are provided in the insideof the camera head 11102 such that reflected light (observation light)from the observation target is condensed on the image pickup element bythe optical system. The observation light is photo-electricallyconverted by the image pickup element to generate an electric signalcorresponding to the observation light, namely, an image signalcorresponding to an observation image. The image signal is transmittedas RAW data to a camera control unit (CCU: Camera Control Unit) 11201.

The CCU 11201 includes a central processing unit (CPU), a graphicsprocessing unit (GPU) or the like and integrally controls operation ofthe endoscope 11100 and a display apparatus 11202. Further, the CCU11201 receives an image signal from the camera head 11102 and performs,for the image signal, various image processes for displaying an imagebased on the image signal such as, for example, a development process(demosaic process).

The display apparatus 11202 displays thereon an image based on an imagesignal, for which the image processes have been performed by the CCU11201, under the control of the CCU 11201.

The light source apparatus 11203 includes alight source such as, forexample, a light emitting diode (LED) and supplies irradiation lightupon imaging of a surgical region to the endoscope 11100.

An inputting apparatus 11204 is an input interface for the endoscopicsurgery system 11000. A user can perform inputting of various kinds ofinformation or instruction inputting to the endoscopic surgery system11000 through the inputting apparatus 11204. For example, the user wouldinput an instruction or a like to change an image pickup condition (typeof irradiation light, magnification, focal distance or the like) by theendoscope 11100.

A treatment tool controlling apparatus 11205 controls driving of theenergy device 11112 for cautery or incision of a tissue, sealing of ablood vessel or the like. A pneumoperitoneum apparatus 11206 feeds gasinto a body cavity of the patient 11132 through the pneumoperitoneumtube 11111 to inflate the body cavity in order to secure the field ofview of the endoscope 11100 and secure the working space for thesurgeon. A recorder 11207 is an apparatus capable of recording variouskinds of information relating to surgery. A printer 11208 is anapparatus capable of printing various kinds of information relating tosurgery in various forms such as a text, an image or a graph.

It is to be noted that the light source apparatus 11203 which suppliesirradiation light when a surgical region is to be imaged to theendoscope 11100 may include a white light source which includes, forexample, an LED, a laser light source or a combination of them. Where awhite light source includes a combination of red, green, and blue (RGB)laser light sources, since the output intensity and the output timingcan be controlled with a high degree of accuracy for each color (eachwavelength), adjustment of the white balance of a picked up image can beperformed by the light source apparatus 11203. Further, in this case, iflaser beams from the respective RGB laser light sources are irradiatedtime-divisionally on an observation target and driving of the imagepickup elements of the camera head 11102 are controlled in synchronismwith the irradiation timings. Then images individually corresponding tothe R, G and B colors can be also picked up time-divisionally. Accordingto this method, a color image can be obtained even if color filters arenot provided for the image pickup element.

Further, the light source apparatus 11203 may be controlled such thatthe intensity of light to be outputted is changed for each predeterminedtime. By controlling driving of the image pickup element of the camerahead 11102 in synchronism with the timing of the change of the intensityof light to acquire images time-divisionally and synthesizing theimages, an image of a high dynamic range free from underexposed blockedup shadows and overexposed highlights can be created.

Further, the light source apparatus 11203 may be configured to supplylight of a predetermined wavelength band ready for special lightobservation. In special light observation, for example, by utilizing thewavelength dependency of absorption of light in a body tissue toirradiate light of a narrow band in comparison with irradiation lightupon ordinary observation (namely, white light), narrow band observation(narrow band imaging) of imaging a predetermined tissue such as a bloodvessel of a superficial portion of the mucous membrane or the like in ahigh contrast is performed. Alternatively, in special light observation,fluorescent observation for obtaining an image from fluorescent lightgenerated by irradiation of excitation light may be performed. Influorescent observation, it is possible to perform observation offluorescent light from a body tissue by irradiating excitation light onthe body tissue (autofluorescence observation) or to obtain afluorescent light image by locally injecting a reagent such asindocyanine green (ICG) into a body tissue and irradiating excitationlight corresponding to a fluorescent light wavelength of the reagentupon the body tissue. The light source apparatus 11203 can be configuredto supply such narrow-band light and/or excitation light suitable forspecial light observation as described above.

FIG. 80 is a block diagram depicting an example of a functionalconfiguration of the camera head 11102 and the CCU 11201 depicted inFIG. 79.

The camera head 11102 includes a lens unit 11401, an image pickup unit11402, a driving unit 11403, a communication unit 11404 and a camerahead controlling unit 11405. The CCU 11201 includes a communication unit11411, an image processing unit 11412 and a control unit 11413. Thecamera head 11102 and the CCU 11201 are connected for communication toeach other by a transmission cable 11400.

The lens unit 11401 is an optical system, provided at a connectinglocation to the lens barrel 11101. Observation light taken in from adistal end of the lens barrel 11101 is guided to the camera head 11102and introduced into the lens unit 11401. The lens unit 11401 includes acombination of a plurality of lenses including a zoom lens and afocusing lens.

The image pickup unit 11402 includes image pickup elements. The numberof the image pickup elements included by the image pickup unit 11402 maybe one (single-plate type) or a plural number (multi-plate type). Wherethe image pickup unit 11402 is configured as that of the multi-platetype, for example, image signals corresponding to respective R, G and Bare generated by the image pickup elements, and the image signals may besynthesized to obtain a color image. The image pickup unit 11402 mayalso be configured so as to have a pair of image pickup elements foracquiring respective image signals for the right eye and the left eyeready for three dimensional (3D) display. If 3D display is performed,then the depth of a living body tissue in a surgical region can becomprehended more accurately by the surgeon 11131. It is to be notedthat, where the image pickup unit 11402 is configured as that ofmulti-plate type, a plurality of systems of lens units 11401 areprovided corresponding to the individual image pickup elements.

Further, the image pickup unit 11402 may not necessarily be provided onthe camera head 11102. For example, the image pickup unit 11402 may beprovided immediately behind the objective lens in the inside of the lensbarrel 11101.

The driving unit 11403 includes an actuator and moves the zoom lens andthe focusing lens of the lens unit 11401 by a predetermined distancealong an optical axis under the control of the camera head controllingunit 11405. Consequently, the magnification and the focal point of apicked up image by the image pickup unit 11402 can be adjusted suitably.

The communication unit 11404 includes a communication apparatus fortransmitting and receiving various kinds of information to and from theCCU 11201. The communication unit 11404 transmits an image signalacquired from the image pickup unit 11402 as RAW data to the CCU 11201through the transmission cable 11400.

In addition, the communication unit 11404 receives a control signal forcontrolling driving of the camera head 11102 from the CCU 11201 andsupplies the control signal to the camera head controlling unit 11405.The control signal includes information relating to image pickupconditions such as, for example, information that a frame rate of apicked up image is designated, information that an exposure value uponimage picking up is designated and/or information that a magnificationand a focal point of a picked up image are designated.

It is to be noted that the image pickup conditions such as the framerate, exposure value, magnification or focal point may be designated bythe user or may be set automatically by the control unit 11413 of theCCU 11201 on the basis of an acquired image signal. In the latter case,an auto exposure (AE) function, an auto focus (AF) function and an autowhite balance (AWB) function are incorporated in the endoscope 11100.

The camera head controlling unit 11405 controls driving of the camerahead 11102 on the basis of a control signal from the CCU 11201 receivedthrough the communication unit 11404.

The communication unit 11411 includes a communication apparatus fortransmitting and receiving various kinds of information to and from thecamera head 11102. The communication unit 11411 receives an image signaltransmitted thereto from the camera head 11102 through the transmissioncable 11400.

Further, the communication unit 11411 transmits a control signal forcontrolling driving of the camera head 11102 to the camera head 11102.The image signal and the control signal can be transmitted by electricalcommunication, optical communication or the like.

The image processing unit 11412 performs various image processes for animage signal in the form of RAW data transmitted thereto from the camerahead 11102.

The control unit 11413 performs various kinds of control relating toimage picking up of a surgical region or the like by the endoscope 11100and display of a picked up image obtained by image picking up of thesurgical region or the like. For example, the control unit 11413 createsa control signal for controlling driving of the camera head 11102.

Further, the control unit 11413 controls, on the basis of an imagesignal for which image processes have been performed by the imageprocessing unit 11412, the display apparatus 11202 to display a pickedup image in which the surgical region or the like is imaged. Thereupon,the control unit 11413 may recognize various objects in the picked upimage using various image recognition technologies. For example, thecontrol unit 11413 can recognize a surgical tool such as forceps, aparticular living body region, bleeding, mist when the energy device11112 is used and so forth by detecting the shape, color and so forth ofedges of objects included in a picked up image. The control unit 11413may cause, when it controls the display apparatus 11202 to display apicked up image, various kinds of surgery supporting information to bedisplayed in an overlapping manner with an image of the surgical regionusing a result of the recognition. Where surgery supporting informationis displayed in an overlapping manner and presented to the surgeon11131, the burden on the surgeon 11131 can be reduced and the surgeon11131 can proceed with the surgery with certainty.

The transmission cable 11400 which connects the camera head 11102 andthe CCU 11201 to each other is an electric signal cable ready forcommunication of an electric signal, an optical fiber ready for opticalcommunication or a composite cable ready for both of electrical andoptical communications.

Here, while, in the example depicted, communication is performed bywired communication using the transmission cable 11400, thecommunication between the camera head 11102 and the CCU 11201 may beperformed by wireless communication.

It is to be noted that while the description has been given here of theendoscopic surgery system as one example, the technology according to anembodiment of the present disclosure may also be applied to, forexample, a micrographic surgery system and the like.

It is to be noted that the present disclosure may also have thefollowing configurations.

[A01] <<Imaging Element>>

An imaging element including a photoelectric conversion sectionincluding a first electrode, a photoelectric conversion layer includingan organic material, and a second electrode that are stacked, in which

an inorganic semiconductor material layer is formed between the firstelectrode and the photoelectric conversion layer, and

a value ΔEN is less than 1.695, the value ΔEN resulting from subtractingan average value EN_(cation) of electronegativities of cationic speciesincluded in the inorganic semiconductor material layer from an averagevalue EN_(anion) of electronegativities of anionic species included inthe inorganic semiconductor material layer.

[A02] The imaging element according to [A01], in which the ΔEN is 1.624or less.[A03] The imaging element according to [A01] or [A02], in which, whenthe inorganic semiconductor material layer is represented by (A¹ _(a1)A²_(a2)A³ _(a3) . . . A^(M) _(aM))(B¹ _(b1)B² _(b2)B³ _(b3) . . . B^(N)_(bN)) [where A¹, A², A³, . . . , and A^(M) are cationic species, B¹,B², B³, . . . , and B^(N) are anionic species, and a1, a2, a3, . . . ,and aM, and b1, b2, b3, . . . , and bN are values corresponding toatomic percentages, with a total thereof being 1.00],

EN_(anion) = (B1 × b 1 + B 2 × b 2 + B 3 × b 3 . . .+BN × bN)/(b 1 + b 2 + b 3 . . .+bN)EN_(cation) = (A1 × a 1 + A 2 × a 2 + A 3 × a 3 . . .+AM × aM)/(a 1 + a 2 + a 3 . . .+aM)

hold true, where B1, B2, B3, . . . , and BN are electronegativities ofthe anionic species B¹, B², B³ . . . , and B^(N), and A1, A2, A3, . . ., and A^(M) are electronegativities of the cationic species A¹, A², A³ .. . , and A^(M).[A04] The imaging element according to any one of [A01] to [A03], inwhich the cationic species include at least one type of cationic speciesselected from the group consisting of Zn, Ga, Ge, Cd, In, Al, Ti, B, Si,Sn, Hg, Tl, and Pb.[A05] The imaging element according to any one of [A01] to [A03], inwhich the cationic species include Ga, In, and Sn, and the anionicspecies include O.[A06] The imaging element according to any one of [A01] to [A03], inwhich the cationic species include Zn, A1, and Sn, and the anionicspecies include O.[A07] The imaging element according to any one of [A01] to [A06], inwhich the photoelectric conversion section further includes aninsulating layer, and a charge accumulation electrode disposed at adistance from the first electrode and disposed to be opposed to theinorganic semiconductor material layer with the insulating layerinterposed therebetween.[A08] The imaging element according to any one of [A01] to [A07], inwhich the following expression:

E₁ − E₀ ≥ 0.1  eV

is satisfied, where E₀ denotes a LUMO value of a material included in aportion of the photoelectric conversion layer positioned in a vicinityof the inorganic semiconductor material layer, and E₁ denotes a minimumenergy value of a conduction band of an inorganic semiconductor materialincluded in the inorganic semiconductor material layer. [A09] Theimaging element according to [A08], in which the following expression:

E₁ − E₀ > 0.1  eV

[A10] The imaging element according to any one of [A01] to [A09], inwhich the inorganic semiconductor material layer included in theinorganic semiconductor material layer has a carrier mobility of 10cm²/Vs or more.[A11] The imaging element according to any one of [A01] to [A10], inwhich the inorganic semiconductor material layer has a carrier densityof 1×10¹⁶/cm³ or less.[A12] The imaging element according to any one of [A01] to [A11], inwhich the inorganic semiconductor material layer has a thickness of1×10⁻⁸ m to 1.5×10⁻⁷ m.[A13] The imaging element according to any one of [A01] to [A12], inwhich

light is incident from the second electrode,

a surface roughness Ra of a surface of the inorganic semiconductormaterial layer at an interface between the photoelectric conversionlayer and the inorganic semiconductor material layer is 1.5 nm or less,and

a value of a root mean square roughness Rq of the surface of theinorganic semiconductor material layer is 2.5 nm or less.

[A14] The imaging element according to any one of [A01] to [A13], inwhich, when a composition of the inorganic semiconductor materialincluded in the inorganic semiconductor material layer is expressed byA¹ _(a1)Zn_(a2)Sn_(a3)O_(b1) (where a1+a2+a3=1.00 as well as a1>0, a2>0,and a3>0 hold true),

$\begin{matrix}{{{0.8}8 \times \left( {{a3} - {0.3}} \right)} > {{0.1}2 \times a1}} & (1)\end{matrix}$

is satisfied.[A15] The imaging element according to any one of [A01] to [A14], inwhich the inorganic semiconductor material included in the inorganicsemiconductor material layer has an optical gap of 2.8 eV or more and3.2 eV or less.[A16] The imaging element according to any one of [A01] to [A15], inwhich, when the composition of the inorganic semiconductor materialincluded in the inorganic semiconductor material layer is expressed byAl_(a1)Zn_(a2)Sn_(a3)O_(b1) (where a1+a2+a3=1.00 as well as a1>0, a2>0,and a3>0 hold true),

$\begin{matrix}{{{0.3}6 \times \left( {{a\; 3} - {0.62}} \right)} \leq {{0.6}4 \times a\; 1} \leq {0.36 \times a3}} & (2)\end{matrix}$

is satisfied.[A17] The imaging element according to any one of [A01] to [A16], inwhich the inorganic semiconductor material included in the inorganicsemiconductor material layer has an oxygen deficiency generation energyof 2.6 eV or more.[A18] The imaging element according to any one of [A01] to [A17], inwhich, when the composition of the inorganic semiconductor materialincluded in the inorganic semiconductor material layer is expressed byAl_(a1)Zn_(a2)Sn_(a3)O_(b1) (where a1+a2+a3=1.00 as well as a1>0, a2>0,and a3>0 hold true),

$\begin{matrix}{{a3} \leq {0{.67}}} & \left( \text{3-1)} \right. \\{and} & \; \\{{0.60 \times \left( {{a3} - {{0.6}1}} \right)} \leq {{0.4}0 \times a\; 1}} & \text{(3-2)}\end{matrix}$

are satisfied.[A19] The imaging element according to any one of [A01] to [A18], inwhich the inorganic semiconductor material included in the inorganicsemiconductor material layer has an oxygen deficiency generation energyof 3.0 eV or more.[A20] The imaging element according to any one of [A01] to [A05] and[A19], in which, when the composition of the inorganic semiconductormaterial included in the inorganic semiconductor material layer isexpressed by Al_(a1)Zn_(a2)Sn_(a3)O_(b1) (where a1+a2+a3=1.00 as well asa1>0, a2>0, and a3>0 hold true),

$\begin{matrix}{{a3} \leq {0{.53}}} & {\text{(3-}\left. 1^{\prime} \right)} \\{and} & \; \\{{0.35 \times \left( {{a3} - {{0.3}2}} \right)} \leq {{0.6}5 \times a\; 1}} & {\text{(3-}\left. 2^{\prime} \right)}\end{matrix}$

are satisfied.[A21] The imaging element according to any one of [A01] to [A20], inwhich, when the composition of the inorganic semiconductor materialincluded in the inorganic semiconductor material layer is expressed byAl_(a1)Zn_(a2)Sn_(a3)O_(b1) (where a1+a2+a3=1.00 as well as a1>0, a2>0,and a3>0 hold true),

$\begin{matrix}{{a3} \geq {{a2} - {{0.5}4}}} & (4)\end{matrix}$

is satisfied.[A22] The imaging element according to any one of [A01] to [A13], inwhich, when the composition of the inorganic semiconductor materialincluded in the inorganic semiconductor material layer is expressed byM_(a1)N_(a2)Sn_(a3)O_(b1) (where M denotes an aluminum atom, and Ndenotes a gallium atom or a zinc atom, or a gallium atom and a zincatom),

a 1 + a 3 + a 2 = 1.00 0.01 ≤ a 1 ≤ 0.04 and   a 3 < a 2

are satisfied.[A23] The imaging element according to [A22], in which a1<a3<a2 issatisfied.[A24] The imaging element according to any one of [A01] to [A23], inwhich electric charge generated in the photoelectric conversion layermoves to the first electrode via the inorganic semiconductor materiallayer.[A25] The imaging element according to [A24], in which the electriccharge includes an electron.[B01] The imaging element according to any one of [A01] to [A25], inwhich

the inorganic semiconductor material layer includes a first layer and asecond layer from side of the first electrode, and

ρ₁ ≥ 5.9  g/cm³ and   ρ₁ − ρ₂ ≥ 0.1  g/cm³

are satisfied, where ρ₁ denotes an average film density of the firstlayer and ρ₂ denotes an average film density of the second layer in aportion extending for 3 nm, preferably 5 nm, or more preferably 10 nmfrom an interface between the first electrode and the inorganicsemiconductor material layer.[B02] The imaging element according to [B01], in which the first layerand the second layer are identical in composition.[B03] The imaging element according to any one of [A01] to [A14], inwhich

the inorganic semiconductor material layer includes a first layer and asecond layer from side of the first electrode, the first layer and thesecond layer are identical in composition, and

ρ₁ − ρ₂ ≥ 0.1  g/cm³ 

is satisfied, where ρ₁ denotes an average film density of the firstlayer and ρ₂ denotes an average film density of the second layer in aportion extending for 3 nm, preferably 5 nm, or more preferably 10 nmfrom an interface between the first electrode and the inorganicsemiconductor material layer.

[C01] <<Stacked Imaging Element>>

A stacked imaging element including at least one imaging elementaccording to any one of [A01] to [B03].

[D01] <<Solid-State Imaging Device . . . First Mode>>

A solid-state imaging device including a plurality of the imagingelements according to any one of [A01] to [B03].

[D02] <<Solid-State Imaging Device . . . Second Mode>>

A solid-state imaging device including a plurality of the stackedimaging elements according to [C01].

[E01] <<Method of Manufacturing Imaging Element>>

A method of manufacturing an imaging element, the method including:

sequentially forming, on an underlayer in which a first electrode isformed, an inorganic semiconductor material layer, a photoelectricconversion layer including an organic material, and a second electrode,and

applying an annealing process at 250° C. or less in an atmospherecontaining water vapor after the formation of the inorganicsemiconductor material layer.

REFERENCE NUMERALS LIST

-   10 imaging element (stacked imaging element, first imaging element)-   11 second imaging element-   12 third imaging element-   13 various constituent elements of imaging element positioned below    interlayer insulating layer-   14 on-chip microlens (OCL)-   15 light-blocking layer-   21 first electrode-   22 second electrode-   23 photoelectric conversion stack-   23A photoelectric conversion layer-   23B inorganic semiconductor material layer-   24 charge accumulation electrode-   24A, 24B, 24C charge accumulation electrode segment-   25, 25A, 25B transfer control electrode (charge transfer electrode)-   26 charge drain electrode-   27 lower charge movement control electrode (lower side/charge    movement control-   electrode)-   27A connection hole-   27B pad section-   28 upper charge movement control electrode (upper side/charge    movement control-   electrode)-   41 n-type semiconductor region included in second imaging element-   43 n-type semiconductor region included in third imaging element-   42, 44, 73 p+ layer-   45, 46 gate section of transfer transistor-   51 gate section of reset transistor TR1 _(rst)-   51A channel formation region of reset transistor TR1 _(rst)-   51B, 51C source/drain region of reset transistor TR1 _(rst)-   52 gate section of amplification transistor TR1 _(amp)-   52A channel formation region of amplification transistor TR1 _(amp)-   52B, 52C source/drain region of amplification transistor TR1 _(amp)-   53 gate section of selection transistor TR1 _(sel)-   53A channel formation region of selection transistor TR1 _(sel)-   53B, 53C source/drain region of selection transistor TR1 _(sel)-   61 contact hole section-   62 wiring layer-   63, 64, 68A pad section-   65, 68B connection hole-   66, 67, 69 connection section-   70 semiconductor substrate-   70A first surface (front surface) of semiconductor substrate-   70B second surface (back surface) of semiconductor substrate-   71 element separation region-   72 oxide film-   74 HfO₂ film-   75 insulating material film-   76, 81 interlayer insulating layer-   82 insulating layer-   82 _(A) region between adjacent imaging elements (region-a)-   83 protection material layer-   84 opening-   85 second opening-   100 solid-state imaging device-   101 stacked imaging element-   111 imaging region-   112 vertical drive circuit-   113 column signal processing circuit-   114 horizontal drive circuit-   115 output circuit-   116 drive control circuit-   117 signal line (data output line)-   118 horizontal signal line-   200 electronic apparatus (camera)-   201 solid-state imaging device-   210 optical lens-   211 shutter device-   212 drive circuit-   213 signal processing circuit-   FD₁, FD₂, FD₃, 45C, 46C floating diffusion layer-   TR1 _(trs), TR2 _(trs), TR3 _(trs) transfer transistor-   TR1 _(rst), TR2 _(rst), TR3 _(rst) reset transistor-   TR1 _(amp), TR2 _(amp), TR3 _(amp) amplification transistor-   TR1 _(sel), TR3 _(sel), TR3 _(sel) selection transistor-   V_(DD) power Supply-   RST₁, RST₂, RST₃ reset line-   SEL₁, SEL₂, SEL₃ selection line-   117, VSL, VSL₁, VSL₂, VSL₃ signal line (data output line)-   TG₂, TG₃ transfer gate line-   V_(OA), V_(OB), V_(OT), V_(OU) wiring line

1: An imaging element comprising a photoelectric conversion sectionincluding a first electrode, a photoelectric conversion layer includingan organic material, and a second electrode that are stacked, wherein aninorganic semiconductor material layer is formed between the firstelectrode and the photoelectric conversion layer, and a value ΔEN isless than 1.695, the value ΔEN resulting from subtracting an averagevalue EN_(cation) of electronegativities of cationic species included inthe inorganic semiconductor material layer from an average valueEN_(anion) of electronegativities of anionic species included in theinorganic semiconductor material layer. 2: The imaging element accordingto claim 1, wherein the ΔEN is 1.624 or less. 3: The imaging elementaccording to claim 1, wherein, when the inorganic semiconductor materiallayer is represented by (A¹ _(a1)A² _(a2)A³ _(a3) . . . A^(M) _(aM))(B¹_(b1)B² _(b2)B³ _(b3) . . . B^(N) _(bN)) [where A¹, A², A³, . . . , andA^(M) are cationic species, B¹, B², B³, . . . , and B^(N) are anionicspecies, and a1, a2, a3, . . . , and aM, and b1, b2, b3, . . . , and bNare values corresponding to atomic percentages, with a total thereofbeing 1.00],EN _(anion)=(B1×b1+B2×b2+B3×b3 . . . +BN×bN)/(b1+b2+b3 . . . +bN)EN _(cation)=(A1×a1+A2×a2+A3×a3 . . . +AM×aM)/(a1+a2+a3 . . . +aM) holdtrue, where B1, B2, B3, . . . , and BN are electronegativities of theanionic species B¹, B², B³ . . . , and B^(N), and A1, A2, A3, . . . ,and A^(M) are electronegativities of the cationic species A¹, A², A³ . .. , and A^(M). 4: The imaging element according to claim 1, wherein thecationic species include at least one type of cationic species selectedfrom the group consisting of Zn, Ga, Ge, Cd, In, Al, Ti, B, Si, Sn, Hg,Tl, and Pb. 5: The imaging element according to claim 1, wherein thecationic species include Ga, In, and Sn, and the anionic species includeO. 6: The imaging element according to claim 1, wherein the cationicspecies include Zn, Al, and Sn, and the anionic species include O. 7:The imaging element according to claim 1, wherein the photoelectricconversion section further includes an insulating layer, and a chargeaccumulation electrode disposed at a distance from the first electrodeand disposed to be opposed to the inorganic semiconductor material layerwith the insulating layer interposed therebetween. 8: The imagingelement according to claim 1, wherein the following expression:E ₁ −E ₀≥0.1 eV is satisfied, where E₀ denotes a LUMO value of amaterial included in a portion of the photoelectric conversion layerpositioned in a vicinity of the inorganic semiconductor material layer,and E₁ denotes a minimum energy value of a conduction band of aninorganic semiconductor material included in the inorganic semiconductormaterial layer. 9: The imaging element according to claim 8, wherein thefollowing expression:E ₁ −E ₀>0.1 eV is satisfied. 10: The imaging element according to claim1, wherein the inorganic semiconductor material layer has a carriermobility of 10 cm²/V·s or more. 11: The imaging element according toclaim 1 wherein the inorganic semiconductor material layer has a carrierdensity of 1×10¹⁶/cm³ or less. 12: The imaging element according toclaim 1, wherein the inorganic semiconductor material layer has athickness of 1×10⁻⁸ m to 1.5×10⁻⁷ m. 13: The imaging element accordingto claim 1, wherein light is incident from the second electrode, asurface roughness Ra of a surface of the inorganic semiconductormaterial layer at an interface between the photoelectric conversionlayer and the inorganic semiconductor material layer is 1.5 nm or less,and a value of a root mean square roughness Rq of the surface of theinorganic semiconductor material layer is 2.5 nm or less. 14: A stackedimaging element comprising at least one imaging element according toclaim
 1. 15: A solid-state imaging device comprising a plurality of theimaging elements according to claim
 1. 16: A solid-state imaging devicecomprising a plurality of the stacked imaging elements according toclaim
 14. 17: A method of manufacturing an imaging element, the methodcomprising: sequentially forming, on an underlayer in which a firstelectrode is formed, an inorganic semiconductor material layer, aphotoelectric conversion layer including an organic material, and asecond electrode; and applying an annealing process at 250° C. or lessin an atmosphere containing water vapor after the formation of theinorganic semiconductor material layer.